CN2337566Y - Multifunction digital universal meter capable of being as a pen - Google Patents

Abstract

The utility model relates to a multifunction digital universal meter capable of being produced into a pen shape. In the multifunction digital universal meter, a K11, a D11 and a C11 are added skillfully in a digital universal meter for being capable of measuring high-frequency and pulse signals; a K21, an R21-22 and an LED are added for being capable of measuring forward and reverse on-state voltage of p-n nodes, the short circuit of coils, resistors with less than 1/100 ohm and positioning short dots on a printed board; an R31-38, a C31-34 and a T31-32 are added for being capable of outputting audio signals and trace hunting audio signals; a K41 and an R41-42 are added for capable of measuring alternating current-direct current with amperes. All added function steps also use a probe and concentric lines of an original meter in common. Added elements is designed into one element with multi-function to the greatest extent, and therefore, the multifunction digital universal meter can also keep the volume of a general pen-shaped meter with minimum volume and has the advantages of simple circuit and low cost. Most of steps which are not used generally are converted by a self-resetting switch, and therefore, the operation is simple. The multifunction digital universal meter has a model machine.

Description

Can make the multifunctional digital multimeter of pen type

The utility model relates to a kind of multifunctional digital multimeter of making pen type, is a kind of electronic detecting means.

Existing digital multimeter can not be used for the measured frequency higher signal, have in addition survey non-power frequency component error and just obviously strengthen (see 95 years " electronics newspaper bound volume " volume two 354 pages); Though useful external wave detector is surveyed high-frequency signal, and is very inconvenient; It also still is zero that some digital multimeter are measured 6 ohm resistance readings, and some are worth more than 2000 yuan digital multimeter low-resistance shelves measuring error and also reach+/-2 words, and this just can't measure little resistance and short circuit of beatting up nurse to a few percent; Though in multimeter plus signal generator is arranged, and volume is bigger, cost is higher and add terminal; Sound of no use tracks and indicates the function of electric signal in the existing multimeter; Because restriction such as switch rated current, existing ordinary numbers multimeter are surveyed the many special-purpose sockets in addition of the electric current that surpasses 1 ampere and inconvenience, how the pen type digital multimeter can only survey electric current below 0.2 ampere and have can't survey electric current.Though the instrument that has has above-mentioned discrete function, the cost height, volume is big, terminals are many, function singleness, troublesome poeration.

The utility model is when keeping minimum volume pen type digital versatile table function, volume and leading-out wire radical, and a kind of multifunctional digital multimeter of making pen type that provides.

The purpose of this utility model can reach by the following technical programs.As shown in Figure 1, it is to survey voltage/measuring resistance signal input part (A) in common pen type digital multimeter to be connected to electric capacity (C11) and switch (K11), is connected to rectification, coupling, protection, amplification and the oscillatory circuit that diode (D11), resistance (R31-38), electric capacity (C31-34), diode (ZD21, ZD31, D31) and triode (T31-32) constitute by switch (K11) again; Go up at common pen type digital multimeter probe (P) and to be connected to single-pole switch (K21) by fuse (F11), again by be connected between switch (K21) and the positive supply (V+) resistance (R21), and be connected to resistance (R22) and light emitting diode (LED) series circuit between (COM); Survey current signal input end (B) in common pen type digital multimeter and be connected to switch (K41), again by being connected to resistance (R41) between switch (K41) and the negative supply (V-).

In such scheme, positive supply (V+) is received diode (D31) and triode (T32) by switch (SB).

The utility model compares with existing pen type digital multimeter that the many and existing multiple function apparatus of function is lower than cost, volume is little, connection terminal lacks, simple to operate; It has increased survey high frequency and pulse signal, the forward and reverse and forward voltage of survey p-n junction, surveys to beat up the resistance of nurse, the sound signal of exporting and track, survey and surpass 1 ampere ac and dc current function to one of percentage for a short time.

Accompanying drawing 1 is a circuit diagram of the present utility model.

Accompanying drawing 2 is shape assumption diagrams of the present utility model.

Accompanying drawing 3 is Fig. 1 circuit audio signal output waveforms.

Below in conjunction with accompanying drawing the utility model is described further.

The position of the switch has as shown in Figure 1 kept the function of existing digital multimeter, and its method of surveying voltage and resistance repeats no more here with original the same.

When surveying high frequency and pulse signal, on the selection basis of former table survey DC voltage K11 is thrown the RF shelves, D11 and C11 become measured signal into DC voltage for showing.

When surveying the forward and reverse and forward voltage of p-n junction, survey at former table on the selection basis of DC voltage self-resetting switch K21 is depressed, the voltage of surveying is p-n junction forward conduction voltage.

As shown in Figure 1, when surveying small resistor, L0 Ω shelves can think that the electric current that flows through on the measured resistance is 0.1mA; Being 10mA behind the Closing Switch K21, is original 100 times, and it also is original 100 times that resistance value shows.When surveying small resistor, on the basis of former L0 Ω shelves, K21 depresses with self-resetting switch, reading under the short circuit test pencil postscript.The reading that the reading that obtains during with the measurement small resistor deducts under the short circuit test pencil postscript obtains the small resistor value of surveying divided by 100 again.The 1CM length enameled wire that is 0.07mm with this method measurement diameter could cause that 5 readings change! This is to utilize Δ x/ (Δ x+1)=Δ x principle, on the digital multimeter integrated package of rule of three measuring resistance with adding the little resistance value to 1/100 ohm of accurate constant flow source measuring.

When detecting sound signal, on the selection basis when measuring voltage K11 is thrown the AF shelves.Measured signal is indicated by the BZ sounding after T31-32 amplifies via C11, C31, R31-32 and C31 coupling.The effect of this function is to detect pulse or whether voice signal exists, whether whether oscillator exchange observational measurements such as interference on starting of oscillation and the direct supply.Detect the 50mV of 1kHz _P-pSquare wave is easy to hear apart from table 25CM place, detects the 10Hz square wave and also can hear, because wherein contain abundant harmonic wave.

Only just can select to change survey high and low frequency signal circuit, just can select convert audio signals to track and the external coupled circuit of generator with single-pole triple-throw (SPTT) K switch 11.

During output audio signal, all switches are identical when detecting sound signal, and the reading maintained switch SB of closed former table makes it increase one-level amplifier and positive feedback and self-sustained oscillation, and signal is via C11, C31, R31-32 and C31-32 coupling coupling output.Its output is 3000mV on the 100K Ohmage _P-p, be 1000mV on the 10K Ohmage _P-p, be 20mV on 150 Ohmages _P-pIt is output as 1KHz when unloaded, and its frequency is followed load to increase the weight of and risen slightly.Its output waveform as shown in Figure 3.As can be seen, wherein containing abundant harmonic wave can utilize.This function is mainly used in to audio or video circuit such as sound equipment or TVs injects signal, according to sound on loudspeaker or the video screen or image change failure judgement.

When measuring interchange or DC current, be respectively on the basis of measuring interchange or DC voltage, to depress single-pole double-throw switch (SPDT) K41.The conversion one of K41 is to have introduced current sampling resistor R43, the 2nd, and allow R41 draw V/ Ω/A terminal potential to V-, make integrated circuit select to measure current status.This has not only simplified circuit, and the switch that measured electric current is only flowed through increased and needn't worry the size of the measured electric current of current capacity capabilities limits of former Gear-shift switch.

C6, ZD31 and R31-32 are used to prevent tested impacting with high pressure integrated circuit; F21 and ZD21 can prevent to misapply the low resistance shelves and measure curtage and make flow through integrated circuit and with its damage of big electric current accident; F11 can prevent to misapply current gear and measure super-high-current or voltage and make flow through integrated circuit and with its damage of big electric current accident; 2K resistance R 7 is used to alleviate the electric current burden that is increased to integrated circuit by R21 when surveying small resistor.F11 and F21 are the fuses that exactly likes 1/8W resistance.D31 is clamped on the COM earth potential with the HOLD terminal potential of integrated circuit when not depressing SB.This design is convenient to just in case the reparation after selecting wrong grade to burn out.

Claims (2)

1. the multifunctional digital multimeter that can make pen type, it forms in common pen type digital multimeter; (V/ Ω/A) end, integrated circuit (IC1), clock circuit (IC2) and reading maintained switch (SB) constitute common pen type digital multimeter by probe (P), survey voltage/measuring resistance signal input part (A), survey current signal input end (B), survey voltage/measuring resistance/survey electric current selection; It is characterized in that: survey voltage/measuring resistance signal input part (A) in common pen type digital multimeter and be connected to electric capacity (C11) and switch (K11), be connected to rectification, coupling, protection, amplification and the oscillatory circuit that diode (D11), resistance (R31-38), electric capacity (C31-34), diode (D11, ZD21, ZD31, D31) and triode (T31-32) constitute by switch (K11) again; Go up at common pen type digital multimeter probe (P) and to be connected to single-pole switch (K21) by fuse (F11), again by be connected between switch (K21) and the positive supply (V+) resistance (R21), and be connected to resistance (R22) and light emitting diode (LED) series circuit between (COM); Survey current signal input end (B) in common pen type digital multimeter and be connected to switch (K41), again by being connected to resistance (R41) between switch (K41) and the negative supply (V-).

2. multifunctional digital multimeter according to claim 1 is characterized in that: positive supply (V+) is received diode (D31) and triode (T32) by switch (SB).