US3407312A

US3407312A - Timer

Info

Publication number: US3407312A
Application number: US488650A
Authority: US
Inventors: James N Pearse; Paul R Dykstra; Joseph C Mayer
Original assignee: Allen Bradley Co LLC
Current assignee: Allen Bradley Co LLC
Priority date: 1965-09-20
Filing date: 1965-09-20
Publication date: 1968-10-22
Anticipated expiration: 1985-10-22

Description

Oct. 22, 1968 j PEARSE ET AL 3,407,312

TIMER Filed Sept. 20, 1965 3 Sheets-Sheet 1 vfiuzwgv 1. 3.

'y7// INVENTOR. ljg. 5. QNE RND $SE JOSEPH C. MAYER Oct- 22, PEARSE T AL TIMER Filed Sept. 20, 1965 s Sheets-Sheet 2 UN-DELAY A /44 f INVENTOR.

JAMES N. PEARSE PAUL R. DYKSTRA JOSEPH C. MAYER Oct. 22, 1968 PEARSE ET AL 3,407,312

I TIMER Filed Sept. 20, 1965 I v 3 Sheets-Sheet 5 4. OFF DELAY /44 42 OFF DELAY-Z g r I l /4A 306 304 a 8 INVENTOR r4929 JAMES N. PEARSE PAUL R. DYKSTRA JOSEPH. C. MAYER United States Patent 3,407,312 TIMER James N. Pearse, Menomonee Falls, Paul R. Dykstra,

Brookfield, and Joseph C. Mayer, Milwaukee, Wis., assignors to Allen-Bradley Company, Milwaukee, Wis., a corporation of Wisconsin Filed Sept. 20, 1965, Ser. No. 488,650 13 Claims. (Cl. 307-141) ABSTRACT OF THE DISCLOSURE An electrical timer providing alternative On and Offdelay operation through an output switch which responds to magnetic flux and can be operated by a net flux from opposing fluxes. The On and Oflf timing functions can be selected by an integral switch.

This invention is directed to a timer and more particularly an electric timer in which both On and Oildelay functions are available in and integral to a single timer unit.

One significant disadvantage which is found in those available timers resides i the fact that the On and Olfdelay functions are not integral with the unit. That is, rather extensive changes and revisions are necessary to convert available units from the On to the Off-delay function and vice versa. By incorporating both the On and Off-delay functions within the timer unit, such that a minimum change is required therein, the unacceptability and inherent inefiiciency of the available timers has been overcome.

Therefore, it is an object of this invention to provide an electric timer in which switching means for selecting both On and Off-delay functions are integral to the timer unit.

It is a further object of this invention to provide an electric timer in which a minimum of physical change to the timer structure is necessary in order to convert from On to Off-delay or vice versa.

It is a further object of this invention to provide an electric timer in which the timed, output switch responds to magnetic flux sources, which sources oppose each other at the end of a timed Off-delay.

A still further object of this invention is to provide an electric timer utilizing a minimum of components to thereby permit a compact, timer package, without aifecting timer efficiency.

A still further object of this invention is to provide for an electric timer in which structure for both On and Off-delay functions is integral to the timer unit and in which the timed, output switch responds to magnetic flux sources. In particular, the integral structure comprises a switching unit with separate positions for the On and Offdelay.

These and other objects will become more apparent from the following .detailed description and drawings which are illustrative of the invention. The reader is directed to the appended claims which set forth the scope of the invention.

In the drawings:

FIGURE 1 is an isometric view of the electric timer.

FIGURE 2 is a partial, cross-sectional end view of the timer as set forth in FIGURE 1. In this figure, the crosssection is taken along the line 22 of FIGURE 1 with the integral switching unit, to be described later, removed in order to show the connecting pins thereunder.

FIGURE 3 is a partial, cross-sectional plan view of the timer unit taken along line 3-3 of FIGURE 1, but with the integral switching unit removed as in FIGURE 2.

- FIGURE 4'is an isometric view of an integral switch- 3,407,312 Patented Oct. 22, 1968 ing unit in the form of a plug-in module assembly which has been removed from FIGURES 2 and 3 but is seen in FIGURE 1.

FIGURE 5 is a cross-sectional, side view of the module assembly in FIGURE 4 taken along line 55 of FIG- URE 4.

FIGURE 6 is a circuit diagram of the timer circuit, including a representation plus Connection thereto of the connecting pin. The heavier lines of the circuit diagram represent the current flow during the On-delay function.

FIGURE 6a is a detailed view of the timer operating coils when used with an illustrative flux responsive switch.

FIGURE 7 is the circuit diagram of FIGURE 6 but with the heavier lines indicating current flow during the initial stage of the Off-delay function.

FIGURE 8 depicts the second stage of the Oil-delay function as indicated by the current flow through the heavier lines.

FIGURE 9 shows the adaptation of the timer circuits in FIGURES 6 through 8 so as to provide sequential On and Off-timed function.

The generally accepted definitions of the words Ondelay and Off-delay are intended by the usage herein. Specifically, On-delay means a time interval between initiation and a closing of a circuit or operation of the unit controlled by the timer. Olf-delay is that time interval between initiation and opening of a circuit or discontinuing operation of the unit controlled by the timer.

The timer 1 is made up of a base unit 2 and a top block 3. At the end of the top block 3 is an integral switch unit shown here as an independent plug-in module assembly 4 which will be described in greater detail later. Completing the basic components of the timer 1 is the top cover 5.

The base unit 2 houses the timer circuit to be described later and is designed to be seated on top of and be attached to an electromagnetic relay, such as the Allen- Bradley Bulletin 700 N Relay. The attachment of the timer unit 1 to such an electromagnetic relay is achieved through compatible slot construction such as that shown at 8 in the base 2 as well as the lug 9 with aperture 10. Attaching screws (not shown) may be provided to unite the timer 1 with a relay through the aperture 10.

The top block 3 comprises pairs of terminals 14a, 14b, and (see FIGURE 3) with their respective terminal clamps 15a, 15b and and terminal screws 16a, 16b and 16c. Barriers 19 are located between each of the terminals 14, so as to prevent arcing therebetween, and at that end of top block 2 which is opposite from the module assembly 4.

The top cover 5 is secured to the top block 3 by means of screws 20. Also secured to the top cover 5 is the adjustment portion of a variable resistor 21 to be described later in connection with the timer circuit. A remote terminal 23 is located in the top cover 5 and is utilized when remote control is desired such as that achieved through adjustment 21 for the variable resistor. The top cover 5 is blanked to provide an indicator opening 24 immedi ately above the module assembly 4. Since the module assembly 4 position is changed degrees for the On and Off-delay function (as will be described later), both functions have been labeled on the module assembly 4 such that the appropriate label will be visible through the indicator opening 24.

The module assembly 4 is shown in greater detail in FIGURES 4 and 5. As can be seen when comparing FIGURES 2 and 3 with FIGURES 4 and 5, the contacts 28 which are located within the slots 29 slide down over the pin 30 so as to establish contact therebetween. The positioning of these contacts 28 with respect to the pins 30 is very important to the construction illustrated in these drawings. Adjacent contacts 28 are joined in a bifurcated shape so as to make contact between those two adjacent pins 30 over which they slide. The particular two'pins 30 to which the contacts 28 connect when the module assembly 4 is connected to the timer 1 varies. This will be illustrated by FIGURE 4 in which it is seen that the contacts 28 form essentially a center row with the remaining portion of each contact 28 falling on one or the other side of that center line. It can be seen with reference to FIGURE 3 that this center row of contacts 28corresponds to a center row of pins 30 such that when the contacts 28 engage the pins 30, only those pins on one side or the other of the center line will be connected. This relationship between the contacts 28 and pins 30 will be expanded upon in the description of FIGURES 6 through 9.

Turning to the circuit and the components which are to be used in the timer of this invention, the reader is directed to FIGURES 6 through 8. Since the circuit in each of these figures is essentially the same, FIGURE 6 will be referred to for the initial description of circuit components followed by the variations disclosed in FIG- URES 7 and 8, with the description of operation to follow thereafter.

Applied to one of the pairs of terminals, for example terminal 14a, is a desired DC source voltagealthough it may be possible to incorporate the necessary power supply and/or AC to DC conversion means with the timer 1 such that the terminals 14a would be connected to a normally available voltage source. Connected across the voltage source is a timer unit built around a switch which is voltage sensitive to thereby operate after a preselected time interval corresponding to a preselected voltage at the switch. An example of such a voltage sensitive switch is the unijunction transistor 40 shown with its bases, B1 and B2, and emitter E. Here, in a well-known manner, as set forth for example at page 198 of the Transistor Manual, sixth edition, Copyright 1962 by the General Electric Company, the unijunction 40 is connected in parallel to a variable resistor 42 and capacitor 41 with the emitter E connected therebetween. A discharge of the capacitor 41 establishes a suflicient voltage between the emitter E and base B1, at the unijunction transistor 40, to thereby forward bias the transistor, i.e. close the timer unit switch.

This above-mentioned portion of the circuit supplies a timing function for the output switch 46 which in turn responds to a control means to be described hereafter. Although the description that follows refers to the particular flux responsive output switch 46- shown in the drawing, it is to be noted that switch 46 may take other forms such as available through solid state switches.

With the timer unit switch or unijunction transistor 40 closed, a magnetic flux source connected in series therewith, herein shown as coil 43, is able to supply sufficient flux to operate the output switch 46. For purposes of illustration, this output switch 46 has been shown in the FIGURES 6 through 9 adjacent the operating coils. A specific example as to the relative positioning between the output switch 46 and the coils including the coil 43 is shown in FIGURE 611 such that the switch 46 is surrounded. It will be understood that the output switch 46 of the drawings represents that type of switch which closes in response to flux passing therethrough in a first direction and, when held closed, opens in response to a resultant flux passing therethrough in a second direction. Examples of such switches are sealed switches including the reed switch or the solenoid including the common DC relay using a two winding coil.

Since output switch 46 controls the load or that external operation which is to be electrically timed, the output switch 46 is connected to a terminal pair, for example terminals 140 to which the external load can be connected.

The operating circuit for the coil 43 is completed through an initiating switch 47 which is shown'here connected across one of the source terminals 14a and a connecting terminal 14b.

In order to provide for Off-delay (FIGURES 7 and 8), a holding coil 50 is located in parallel with the timing unit and the coil 43. While holding coil 50 is shown here as the means by which output switch 46 is held closed prior to Off-delay, the holding function may alsobe accomplished by, for example, permanent magnets external to or within the switch--or mechanical latching. The direction offlux to which the operating switch 46 is subjected will be described in more detail with the timer operation; but it should be noted at this point that the Off-delayfu'nction requires a resultant :flux to overcome that which retains output switch 46 in a closed position. In the drawings the flux from the coils 43 must produce a resultant flux which overcomes the holding flux of the coil 50. Sinceit is necessary that coil 5i) be first energized in an Off-delay function in order to e'stablish a closed output switch 46 and a consequential On or energized condition of the external unit to be timed, initiating switch 47 is connected to the coil 50 so as to establish these necessary conditions.

It should also be noted here that the coil 50 can play a role in the On-delay function, especially when the voltage sensitive switch of the timing unit does not maintain a closed condition. The later circumstance arises, for example, when a unijunction transistor is used (see pp. 191- 193 in the abovementioned General Electric Transistor Manual). It being desired that the output switch 46 maintain a closed condition after initial closure while coil 43 is alternately energized and deenergized, holding means become necessary; which means are supplied through coil 50. It should be noted that the use of coil 50durin'g Ondelay requires coil 50 to be operable by' the initiating switch 47. g

In the Off-delay function, the flux of the holding coil 50 is opposed by the overridingflux of the coil 43 at tha't'time when the voltage sensitive switch (unijunction of the timing unit closes-the opposing flux of the coil 43 being sufficient to cause the output switch'46 to open. This Olfdelay function begins by completing acircuit including the timing unit with its voltage sensitive switch (unijunction 40), capacitor 41 and variable resistor 42, as well as the coil 43. This circuit is established, as shown in FIGURE 8, by opening the initiating switch 47 which'has previously short circuited or isolated the timer unit including unijunction 40, capacitor 41 and variable resistor 42.

The availability of an integral switching unit for the On and Off-delay function in the timer 1 is illustrated in the FIGURES 6 through 8. With respect to the

coils

43 and 50, it may be desirable to have flux from each of the coils, with respect to the operated output switch 46, which is additive during the On-delay function and is of such relative strength and direction to provide opposingflux during the Off-delay function. In order to accomplish this flux direction change, the direction of current in one'of the coils-here coil 43 is changed. As is seen from the FIGURES 6 through 8, the pins 30F-30K have been so arranged and connected to the leads of the coils '43 that such current change is possible. For example, the direction of current flow in FIGURE 6 is established by the contacts 28 of the module 4 connecting pin 30G with 30H and 301 with 30K. To change the deenergized, holding means become necessary; which means are supplied through coil 50. 'It should be noted that the use of coil 50 during On-delay requires coil 50 to be operable by the initiating switch 47. 4

In the Off-delay function, the flux of the holding coil 50 is opposed by the overriding flux of the coil 43 at that time when the voltage sensitive switch (unijunction 40) of the timing unit closes-the opposing flux of the coil 43 being sufficient to cause the output switch 46 to open. This.

Ofi-delay function begins by completing a circuit includ: ing the timing unit with its voltage sensitive switch (unijunction 40), capacitor 41 and variable resistor 42, as well as the coil 43. This circuit is established, as shown in FIG- URE 8, by opening the initiating switch 47 which has previously short circuited or isolated the timer unit including unijunction 40, capacitor 41 and variable resistor 42.

coils

43 and 50, it may be desirable to have flux from each of the coils, with respect to the operated output switch 46, which is additive during the On-delay function and is of such relative strength and direction to provide opposing flux during the Off-delay function. In order to accomplish this flux direction change, the direction of current in one ofthe coilshere coil 43 is changed. As is seen from the FIG- URES 6 through 8, the pins F-30K have been so arranged and connected to the leads of the coils 43 that such current change is possible. For example, the direction of current flown in FIGURE 6 is established by the contacts 28 of the module 4 connecting pin 306 with 30H and 30] with 30K. To change the current flow in the coil 43, the position of module 4 with respect to the base 2 is changed such that the contacts 28 connect pin 30F with 30G and 301 with 30].

It should be noted, here, that when holding coil 50 is to be used in the On-delay function, for example, when a unijunction transistor is used, the flux of the two coils 43 and may nevertheless oppose each other, thus obviating the need to reverse one of the coils for Off-delay function. However, the use of opposing flux during the On-delay function is an inefficient use of the coils since coil 43 not only would have to supply flux necessary to operate the switch 46, but also supply that additional flux necessary to overcome the opposing flux of coil 50.

Pins 30A30E have been connected to illustrate connections which form the integral switching unit for selecting On and Off-delay within the timer unit 1--but excluding the previouslyoescribed flux switch for coil 43. Here, as shown in FIGURE 6, the

pins

30D and 30E are connected by the contacts 28 when On-delay is desired so that the timer unit consisting of unijunction 40, capacitor 41 and variable resistor 42 will respond to the initiating switch 47. By reversing the position of the module 4 such that the

pins

30A and 30B as well as 30C and 30D are joined by the appropriate contacts 28 (see FIGURES 7 and 8), the holding coil 50 will respond to initiating switch 47 through

pins

30D and 30B while at the same time isolating the timing unit. When the initiating switch 47 opens to initiate the Off-duty timing function, the circuit to the timer unit is completed via pins 30A and 303 as will be more fully explained in the timer operation.

The operation of the illustrated timer circuit is as follows: Referring first to the On-delay as set forth in FIG- URE 6, the initiating switch 47 is connected in series with the operating coil 43 for the output switch 46 as Well as the voltage sensitive switch of the timing unit, i.e.,

the unijunction transistor 40. The initiating switch 47 also controls the timing circuit for the voltage sensitive elements, i.e., variable resistor 42 and capacitor 41. This connection of initiating switch 47 is established through the appropriate contact 28 of the module 4 connecting

pins

30D and 30E. Therefore, when the initiating switch 47 is closed to initiate the On-delay function, the capacitor 41 is charged. The variable resistor 42 is set so as to determine the charging time of capacitor 41, i.e., the length of time after the closing of initiation switch 47 before the capacitor 41 will discharge. Upon the discharge of capacitor 41, the voltage sensitive switch or unijunction transistor 40 is biased forward so as to carry current from the voltage source terminal 14a through the operating coil 43 by way of pins 30] and 30K as well as 30G and 30H. Contact has been made between the last-mentioned pins by engagement of the appropriate contacts 2.8 and the module 4. The circuit through the operating coil 43 is completed by way of the

pins

30D and 30B, the terminal 14B, the

6 closed initiating switch 47 and terminal 14A. The coil 43 is designed with sufficient turns for the current to be passed therethrough such that the resulting flux will close the output switch 46.

As is mentioned above, the use of a voltage sensitive switch which does not remain closed, e.g. the unijunction 40, may require a holding coil such as coil 50 to be energized at least upon the closing of output switch 46. Since the flux necessary to maintain output switch 46 in a closed condition is generally less than that necessary to close this switch, the ampere-turns (NI) of coil 50 when used for holding is most desirably less than that of coil 43. However, Off-delay may require coil 50 to supply more flux than needed for On-delay. The circuit illustrated by FIGURE 6 contemplates those requirements by reducing the current to coil 50 during On-delay through the use of resistor 52 located in series with both coil 50 and the initiating switch 47 during On-delay. As previously noted, the relative direction of the flux from

coils

43 and 50 is not critical insofar as operability of Ondelay, but the operating efficiency of switch 46 along with minimum needed flux source size would dictate additive flux, i.e. the flux of

coils

43 and 50 being in substantially the same direction through the output switch 46.

In order that this same timer 1 operates with an Offdelay function (FIGURES 7 and 8), the module 4 is rotated 180 degrees such that the appropriate contacts 28 connect the

pins

30A and 30B, 30C and 30D, 30F and 306, and 301 and 30]. This change in the pin contact can be seen when comparing FIGURES 7 and 8 with FIGURE 6. The Off-delay function requires that the output switch be closed, i.e. the unit which is to be timed in and On or energized condition. Therefore, the Off-delay function is shown in two steps by means of FIGURES 7 and 8, respectively.

The closing of the output switch 46 is established through the holding coil 50 with the closing of the initiating switch 47. When greater flux is necessary for closing the switch 46 than was necessary for holding the switch 46 closed, the resistor 52-by which flux of the coil 50 is reduced when in series therewithis short circuited during the initial step of the Off-delay. This short circuit is accomplished by passing the current through a path of lesser resistance, viz. diode 53, the pins 306; and 30D, terminal 14b, closed initiating switch 47 and terminal 14a. It is also necessary during this initial step of the Off-delay function that the voltage sensitive switch or unijunction transistor 40, along with the timer circuit connected therewith, must be isolated or inoperative. Therefore, this timer circuit is short circuited by way of diode 54 which is connected so as to by-pass the capacitor 41 and thereby direct the current to the

pins

30C and 30D along with that from the holding coil.

To initiate the time interval before Off-delay, the initiating switch 47 is opened to thereby interrupt the path of least resistance via the

pins

30C and 30D, i.e. the short circuit of the timing circuit and capacitor 41. Because of the connection across

pins

30A and 30B to the source terminal 14a, the timing circuit incorporating capacitor 41 is completed so that the capacitor 41 once again charges for a preselected time interval determined by the variable resistor 42. The discharge of capacitor 41 forward biases the unijunction 40 and energizes the switch 46 through operating coil 43.

As mentioned above, the relative flux direction between the

coils

50 and 43 at the end of the Off-delay time interval must establish a resultant flux which will open the operating switch 46, e.g. cancel the holding flux of coil 50. The particular flux value of the

coils

43,and 50 may be considered a'matter of design; but a smaller flux demands smaller coils and/ or current which constitute definite design advantages. Therefore, while it is not necessary that the flux of coil 50 be reduced after this coil has closed the output switch 46, such reduction in flux is advantageous since the holding flux which coil 43 must overcome for switch 46 opening is thereby reduced. Reduction of coil 50 flux is accomplished through the introduction of resistor 52 into series connection with the coil 50 upon the opening of initiation switch 47. Thus, the current from both

coils

43 and 50 pass through the

pins

30A and 30B which are joined by the appropriate contacts 28 of the module 4 to the terminal 14a.

The need to reverse the current flow in one of the coils 43'or 50 may or may not be necessary as discussed above. However, the circuit diagram of FIGURE 8 illustrates a switching unit integral to the timer 1 through the use of the pins 30 and the contacts 28 to accomplish the current flow reversal in the coil 43. Here, the voltage sensitive switch or unijunction transistor 40 is connected to pin' 30K, which is no longer connected to pin 30] as in the Oii-delay (see FIGURE 6). Instead a cross-connection now connects pin 30K to'pin 30F which, in turn, is connected to pin 30G through an appropriate contact 28 of module 4. The current then flows to the coil 43 in a direction opposite to that in the On-delay of FIGURE 6 and is thereafter directed through corresponding pins 30], 301 and 30H to complete the circuit.

The particular structure used for the integral switching unit, whether to establish the reversal of an operating coil for switch 46 and/or the switching for On and Off timer initiation and operation, is not limited to that shown by the'drawings herein. For example, it would be possible to use manual switches rather than the pins 30 and the plug-in module assembly 4 with its contacts 28. Moreover, the selected integral switching unit is not necessarily limited to switching the particular circuit shown in the drawings. For example, output switch 46 may take the form of a solid state switch with appropriate On-Olf delay control means.

It may also be desirable to have sequential On and Offdelay. FIGURE 9 illustrates a modification of the circuit previously shown in FIGURES 6 through 8 by which such sequencing will be possible. Here, an additional timer unit with-a voltage sensitive switch such as the unijunction transistor 60, a capacitor 61 and a variable resistor 62 are located across the voltage source and correspond to the unijunction transistor 40, capacitor 41 and variableresistor 42, respectively. The voltage sensitive switch or unijunction 60 controls a magnetic flux source or coil 63 to which an initiation switch corresponding to the initiation switch 47 of FIGURE 6 through 8 responds. The sequencing operation is begun by the closing of switch 64.

Since the remaining portions of the circuit are the same as that previously described in FIGURES 6 through 8, it will be apparent that with the closing of switch 64, the coil of 63 is energized after a predetermined time interval. Such energization closes the initiation switch 47 which begins the off-delay function as set forth in the above description and 'FIGURES 7 and 8. That is, the closing of the initiation switch 47 by the coil 63 will energize the holding coil 50 to close the output switch 46. Since the unijunction transistor 60 will subsequently open, due to its inherent characteristics (see discussion above), the coil 63 will be deenergized thereby opening the initiation switch 47. This opening of the switch 47 Will initiate the Oif-delay as in FIGURE 8. By setting the variable resistor 62 such that the time interval for discharge of capacitor 61 is greater than that of the time interval for discharge by capacitor 41, the Off-delay or opening of output switch 46 can be accomplished prior to the reenergization of coil 63 or the beginning of a new cycle. The time interval between opening of the output switch 64 at the end of the Oif-delay time interval and the re closing of switch 64 through the timed closing of initiating switch 64 in response to coil 63 to thereby energize coil 50, represents the On-delay time interval which can be determined through a timer unit adjustment such as variable resistor 62.

We claim: 1. In an electric timer providing alternative On and Off-delay operation,

(a) output switch means operatively responding to magnetic flux from magnetic flux source means for closing in response to said flux in a first direction therethrou gh and opening in response to a resultant flux in a second direction therethrough,

(b) said flux source means comprising first and second portions which supply magnetic flux to said output switch means in said first and second directions,

(c) terminals for an electrical potential source,

(d) timing means comprising timed'switch means connected to said first flux source portion so as to,

, energize said portion after a preselected time inter val and thereby operate said output switch means,

(e) said second flux source portion connected in parallel to said timing means so as to operate said output switch means independently thereof,

(f) first connecting means between said potential source terminals providing:

(1) a first circuit comprising said second flux source portion, and

( 2) a second circuit comprising said timing means and said first fiux portion,

(g) initiating switch terminal means for initiating switch means interrupting said first and second circuits so as to sequentially:

( 1) complete said first circuit and thereby close said output switch, and

(2) complete said second circuit and thereby itiate Off-delay of said output switch, p

(h) said Oif-delay of said output switch effected by said resultant flux comprising the flux of said first flux source portion cancelling the flux of said second flux source portion,

(i) said first connecting means connecting said second circuit to said initiating switch terminal means so as to:

(1) complete said second circuit for initiation of On and Off-delay of said output switch, and

1 (2) isolate said second circuit when said output switch is closed by said first circuit during Off-. delay.

l 2. The electric timer of claim 1 wherein said timed switch means is a unijunction transistor which responds to a timing circuit connected across said potential source terminals. 7

3. The timer of claim 1:providingsequential On and Off-delay wherein,

(a) second timing means comprising second timed switch means which are connected across said potential source terminals,

(b) second flux source means operated by said secon timed switch means,

(c) said initiating switch responsive to said second fluxsource to initiate said OiT-delay of said output switch means, and

((1) said second timing means including time adjust- 6 ing means which establish On-delay of said output switch by permitting delay of. said second timed switch closing until after said Off-delay of said output switch means.

4. The timer of claim 3 wherein said second timed switch means is a unijunction transistor which responds to a timing circuit connected to said potential.

5. The electric timer of claim 1 wherein,

. (a) said timed switch means is a voltage sensitive switch means which responds to a timing circuit connected to said potential, and

',(b) said timing circuit is energized simultaneously with the closing of said second circuit.

6. The timer of claim 5 wherein said voltage sensitive 75 switch means comprises a unijunction transistor.

7. The timer of claim 6 wherein,

(a) second connecting means are connected to at least one of said flux source portions to provide additive magnetic flux from each of said flux source portion,

(b) said first connecting means connecting said second flux portion to said second circuit during On-delay operation of said output switch.

8. The electric timer of claim 6 wherein,

(a) resistance means are located in series with said second flux source portion, and

(b) said first connecting means short circuit said resistance means when said second flux source portion is a part of said first circuit.

9. The electric timer of claim 7 wherein,

(a) resistance means are serially connected with said second flux source portion, and

10. The electric timer of claim 7 wherein,

(a) said first connecting means comprises switch unit means integral with said electric timer which have a first position for connecting said first and second circuits for On-delay and a second position for connecting said first and second circuits for Off-delay, and

(b) said second connecting means comprise switch unit means integral with said electric timer which have a first position to provide for magnetic flux in said first direction at said output switch and a second position to provide for magnetic flux in said second direction at said output switch.

11. In an electric timer energized for alternative On and Off-delay operation,

(a) output switch means operatively responding to magnetic flux from magnetic flux source means for closing in response to said flux in a first direction therethrough and opening in response to a net flux in a second direction therethrough,

(b) said flux course means comprising first and second portions,

(c) electrical timing means to energize said first flux portion after a preselected time interval,

(d) terminals for an electrical potential source,

(e) said output switch means and said timing means connected across said potential source terminals by way of initiating switch terminals means,

(f) said second flux portion connected in parallel with said first portion and said timing means,

(g) housing means for said timer,

(h) switch unit means integral with said housing means,

(i) said switch unit means comprising contact means which,

(1) connect at least one of said flux source portions with said initiation switch terminal means to thereby condition the On-delay of said output switch, and

(2) connect said first and second fiux source portions with said initiating switch terminal means to thereby condition the Off-delay of said output switch,

(j) said switch unit means having first and second positions for said On and Off-delay, respectively.

12. The timer of claim 11 wherein,

(a) said switch unit comprises contact means which connect to at least one of said flux source portions,

(b) said switch unit means connecting at least one of said fiux source portions so that said flux to said output switch means is in said first direction when said unit means is in said first position and in said second direction when said unit is in said second position.

13. The tmer of claim 12 wherein,

(a) said magnetic flux source means comprises coil means,

(b) said electrical timing means comprises, a unijnnction transistor means in series with said first fiux source means and responsive to a timing circuit connected to said potential by way of said initiating switch terminal means,

(c) second resistance means in series with said second fiux portion, and

(d) said switch unit means short-circuiting said second flux portion and said second resistance means during On-delay.

References Cited UNITED STATES PATENTS 2,705,296 3/1955 Weber 317142 X 2,919,385 12/1959 Mierendorf et a1. 317142 3,049,649 8/1962 Burke et al. 317-l41 3,099,758 7/1963 Pieczynski 307-141.8 3,202,884 8/1965 Bullock 317l55.5 X 3,210,614 10/1965 Welk 317-l55.5 X 3,325,657 6/1967 Corey.

ROBERT K. SCHAEFER, Primary Examiner.

50 T. B. JOIKE, Assistant Examiner.