CN201041575Y - A testing circuit for PCB board tester - Google Patents
A testing circuit for PCB board tester Download PDFInfo
- Publication number
- CN201041575Y CN201041575Y CNU2006200654783U CN200620065478U CN201041575Y CN 201041575 Y CN201041575 Y CN 201041575Y CN U2006200654783 U CNU2006200654783 U CN U2006200654783U CN 200620065478 U CN200620065478 U CN 200620065478U CN 201041575 Y CN201041575 Y CN 201041575Y
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- CN
- China
- Prior art keywords
- pnp triode
- resistance
- pcb board
- triode
- test circuit
- Prior art date
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- Expired - Fee Related
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Abstract
The utility model relates to a measuring instrument, in particular to a test circuit of a PCB board test instrument. A test signal source provides constant voltage and is connected with the reflection electrodes of a PNP triode Q1 and a PNP triode Q3, the base electrodes of the PNP triode Q1 and PNP triode Q3 are connected with a signal source SC through being connected with a resistor in series, the collecting electrodes of the PNP triode Q1 and the PNP triode Q3 respectively lead out a metering contact P1 and a metering contact P2, simultaneously the metering contact P1 and the metering contact P2 are respectively connected with the collecting electrodes of a PNP triode Q2 and a PNP triode Q4, and the base electrodes of the PNP triode Q2 and the PNP triode Q4 are respectively connected with a resistor in series, and at the same time are connected with a control source SK. The test circuit with the structure can measure the high voltage contacts, and ensures the precision and the speed of measurement.
Description
Technical field
The utility model relates to a kind of surveying instrument, in particular, is a kind of test circuit of pcb board instrument.
Background technology
The low resistance tester of general PCB generally adopts the current and voltage method test philosophy, also claims four end measuring technologies, and its principle is seen Fig. 1.Supply with measured resistance Rx electric current by current source through " 4,1 " two-port (also claiming the I port), the size of electric current is read by reometer 01.The voltage drop at Rx two ends is taken out by " 2,3 " two ports (also claiming P port, V port), is read by voltage table 02.Know the resistance that just can calculate measured resistance behind I, the V: Rx=V/I.
In order directly to read the numerical value of Rx, can adopt constant current source that the electric current that flows through Rx is remained unchanged, and be a specific integer, so just can directly be carved into the milliohm scale to voltage table 02.Modern milliohmmeter all is digital milliohmmeter.This moment, voltage table 02 was made of the precise electronic amplifier and the digital indicator of high input impedance, can directly demonstrate tested resistance.
The resistance meter of this structure, the electron-amplifier of constant current source technology and high input impedance, thereby resistance, port resistance and the contact resistance etc. of test lead can not impacted to test resistance, but measuring current is big, except that causing the measured piece damage easily, also make the reading drift, test misalignment, and be merely able to the less element of measuring resistance owing to big electric current causes the measured piece heating easily, and measuring speed is slower, can not use high pressure to measure.As electronic voltmeter sensitivity is the 20mV full scale value, if the full test electric current is 100mA, then the highest full scale is 200 milliohms.
Summary of the invention
Of the present utility model at the prior art deficiency, provide a kind of measuring speed fast, counting of measurement is many, and test circuit that can high voltage bearing pcb board instrument.
The test circuit of a kind of pcb board tester that the utility model adopts, testing source provides constant voltage to connect the repeller of two PNP triode Q1, Q3, resistance of this PNP transistor base Q1, Q3 series connection is connected with signal source SC, this PNP triode Q1, Q3 collector are drawn metering contact P1, P2 respectively, metering contact P1, P2 link to each other with the collector of two NPN triode Q2, Q4 respectively simultaneously, the base stage of this NPN triode Q2, Q4 is connected respectively, and also the while is connected this NPN triode Q2, Q4 emitter while resistance in series R to a resistance with Controlling Source SK
sAnd resistance R
f, in resistance R
fAnd the voltage tester table arranged.
The utility model beneficial effect is: by two PNP triode Q1, Q3 and two NPN transistor base Q2, the Q4 that are provided with at metering contact, be connected with PNP triode signal source SC and NPN triode Controlling Source SK respectively, can measure high-tension contact is measured, and can guarantee precision and the speed measured.
Description of drawings:
Fig. 1 is the low resistance tester circuit diagram on the market
Fig. 2 is circuit theory diagrams of the present utility model
Embodiment:
Only be the utility model preferred embodiment below, do not limit protection domain of the present utility model with this.
See shown in Figure 1, the test circuit of a kind of pcb board tester that the utility model adopts, testing source 1 provides constant voltage to connect two PNP triode Q1, the repeller of Q3, this PNP transistor base Q1, resistance of Q3 series connection is connected with signal source SC2, this PNP triode Q1, the Q3 collector is drawn metering contact P1 respectively, P2, while metering contact P1, P2 respectively with two NPN triode Q2, the collector of Q4 links to each other, this NPN triode Q2, the base stage of Q4 is connected respectively, and also the while is connected this NPN triode Q2 to a resistance with Controlling Source SK3, the Q4 emitter is resistance in series R simultaneously
SAnd resistance R
f, in resistance R
fAnd the voltage tester table arranged.
The test circuit of described pcb board tester has 256.
Principle of work of the present utility model is as follows:
Be connected testing resistance R with PIN2 when measuring PIN1
XThe time, voltage source provides constant 12V voltage, and triode switch path Q1 and Q4 are open-minded, and the path of voltage source 1 forms, and electric current flows through R from Q1
X, arrive Rs at last by R through Q4
fGet back to the constant pressure source negative terminal.According to Ohm law I=Vrf/Ref, wherein Vrf: be the voltage that the AD conversion draws, Ref: be known resistance, so the total current on the loop just can draw.Because of test loop is a tandem type, so the electric current of each node equates, so we obtain R=12V-Vrf/I (R=Rq1+Rx+Rq4+Rs, wherein Rq1 resistance is that conducting resistance, the Rq4 resistance of Q1 triode are the conducting resistance of Q4 triode), obtain Rx=R-Rq1-Rq4-Rs (Rq1, Rq4, Rs are known resistances) at last.
The utility model two PNP triode Q1, Q3 and two NPN transistor base Q2, Q4 by being provided with at metering contact, be connected with PNP triode signal source SC2 and NPN triode Controlling Source SK3 respectively, can measure high-tension contact is measured, and can guarantee precision and the speed measured.
Claims (2)
1. the test circuit of a pcb board tester, it is characterized in that: testing source provides constant voltage to connect the repeller of two PNP triode Q1, Q3, resistance of this PNP transistor base Q1, Q3 series connection is connected with signal source SC, this PNP triode Q1, Q3 collector are drawn metering contact P1, P2 respectively, metering contact P1, P2 link to each other with the collector of two NPN triode Q2, Q4 respectively simultaneously, the base stage of this NPN triode Q2, Q4 is connected respectively, and also the while is connected this NPN triode Q2, Q4 emitter while resistance in series R to a resistance with Controlling Source SK
sAnd resistance R
f, in resistance R
fAnd the voltage tester table arranged.
2. the test circuit of pcb board tester according to claim 1 is characterized in that: the test circuit of described pcb board tester has 256.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2006200654783U CN201041575Y (en) | 2006-10-12 | 2006-10-12 | A testing circuit for PCB board tester |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2006200654783U CN201041575Y (en) | 2006-10-12 | 2006-10-12 | A testing circuit for PCB board tester |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201041575Y true CN201041575Y (en) | 2008-03-26 |
Family
ID=39253287
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2006200654783U Expired - Fee Related CN201041575Y (en) | 2006-10-12 | 2006-10-12 | A testing circuit for PCB board tester |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201041575Y (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111413547A (en) * | 2020-05-06 | 2020-07-14 | 苏州市运泰利自动化设备有限公司 | Mainboard resistance test system and method |
-
2006
- 2006-10-12 CN CNU2006200654783U patent/CN201041575Y/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111413547A (en) * | 2020-05-06 | 2020-07-14 | 苏州市运泰利自动化设备有限公司 | Mainboard resistance test system and method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20080326 Termination date: 20101012 |