Is this device suitable for measuring the IDSS of JFETs? Yup, I want to make matched pairs and quads.
Tester Diode Lcr-t4 Meter Npn/pnp Transistor Triode Case Mos 2018 Fet Mega328 | eBay
Tester Diode Lcr-t4 Meter Npn/pnp Transistor Triode Case Mos 2018 Fet Mega328 | eBay
It does not seem so.
You can do this with a DVM and a way to measure the drain current. For example,
measure the voltage drop across a small series resistor, with the source and gate
shorted together. Use a power supply of around 15 or 20VDC. The positive supply
terminal goes on the drain for an N channel, and the opposite for a P channel.
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Should go quickly, just set up a jig with clips, etc. Be sure to observe polarity.
IIRC, my Mega328 displays JFET test current to a resolution of 0.1 ma, i.e. 1.2 ma, 1.3 ma, etc.
If you need more precision then that, or more voltage, then you need to do it some other way.
It would do your fifty JFET's in a matter of minutes. Just stick the device in the ZIF any way you want, push a button, wait a second, results. Likewise for a wide variety of other parts EXCEPT small capacitances, and small inductances less than 2 uH or so.
Win W5JAG
If you need more precision then that, or more voltage, then you need to do it some other way.
It would do your fifty JFET's in a matter of minutes. Just stick the device in the ZIF any way you want, push a button, wait a second, results. Likewise for a wide variety of other parts EXCEPT small capacitances, and small inductances less than 2 uH or so.
Win W5JAG
Then this should be good enough, if the measurements are repeatable.
I've seen some cheap testers give poor results.
AFAIK, yes. There are a couple of versions I think, one has a brighter display, but otherwise the same.
If you get one, make double certain electrolytic caps are discharged. Otherwise, you will be buying a replacement. Learned this the hard way - they come with zero documentation. Fortunately, they are cheap.
Win W5JAG
If you get one, make double certain electrolytic caps are discharged. Otherwise, you will be buying a replacement. Learned this the hard way - they come with zero documentation. Fortunately, they are cheap.
Win W5JAG
The more expensive component testers have a built in battery.
My one just plugs into a USB port for a couple of hours if it gets a bit low on battery power.
I think you need to build a jig for matching FETs and other power devices.
I am still occasionally use a transistor jig I built on the 1970s that does matching over a wide range of Ic. It will soldier on until I find a curve tracer for very little money.
My one just plugs into a USB port for a couple of hours if it gets a bit low on battery power.
I think you need to build a jig for matching FETs and other power devices.
I am still occasionally use a transistor jig I built on the 1970s that does matching over a wide range of Ic. It will soldier on until I find a curve tracer for very little money.
I have this model, and the post I bought it from indeed had all the specs of it's testing abilities.
Indeed, discharge a cap before testing it! This is just good practice, regardless of the tester IMHO.
From the eBay post: LCR-T4 ESR Meter Transistor Tester Diode Triode Capacitance SCR Inductance US | eBay
"Description:
Features :
1,2013 latest M328 version of the software ,more functions.Chip: Atmega328
2.128*64 big Backlight LCD display,only 2mA when stand by.
3,Using 9V battery (Not included)
Test ranges:
Inductors, capacitors , diodes, dual diode , mos, transistor, SCR , the regulator, LED tube , ESR,
Resistance,Adjustable potentiometer
Resistance :0.1 ohm resolution, maximum 50M ohm
Capacitor :25pf -100,000 uf
Inductors : 0.01mh-20H
Function:
1:Automatic detection of NPN and PNP transistors, n-channel and p-channel MOSFET,
diode (including double diode), thyristor, transistor, resistor and capacitor and other components
2: Automatic test the pin of a component, and display on the LCD
3:Can detect the transistor, MOSFET protection diode amplification coefficient
and the base to determine the emitter transistor forward biased voltage
4: Measure the gate and gate capacitance of the MOSFET threshold voltage
5:Use 12864 liquid crystal display with green backlight
Specifications: For you reference
1,One -button operation, automatic shutdown .
2,Only 20nA shutdown current.
3,Automatically detect NPN, PNP bipolar transistors , N -channel and P -channel MOS FET,
JFET , diodes , two diodes, thyristors small power unidirectional and bidirectional thyristor.
4,Automatic identification components pin arrangement .
5,Measuring bipolar transistor current amplification factor and base - emitter threshold voltage.
6,Via the base - emitter threshold voltage and high current amplification factor to identify Darlington transistors.
7,Can detect bipolar transistors and MOS transistors protection diodes.
8,Measuring the gate MOS FET threshold voltage and the gate capacitance.
9,Can simultaneously measure two resistors and resistor symbol is displayed.
Displayed on the right with a decimal value of 4 .
Resistance symbol on both sides shows the pin number.
So you can measure the potentiometer.
If the potentiometer wiper is not transferred to an extreme position ,
we can distinguish the middle and both ends of the pin.
10,Resistance measurement resolution is 0.1 ohms , 50M ohms can be measured .
11,Can measure capacitanceCan measure capacitance of 30pF-100mF , resolution 1pF.
12.2uF more capacitors can simultaneously measure the equivalent series resistance ESR values.
The two can be displayed with a decimal value , resolution 0.01 ohms.
13,Can be in the correct order and the diode symbol display two diodes , and gives the diode forward voltage.
14.LED is detected as a diode forward voltage higher . Combo of the LED is identified as two diodes.
15,Eeverse breakdown voltage is less than 4.5V Zener diode can be identified.
16,Can measure a single diode reverse capacitance.
If the bipolar transistor connected to the base and collector or emitter of a pin ,
it can measure the collector or emitter junction reverse capacitance .
18 can be obtained with a single measurement rectifier bridge connection.
Notice: Before measuring capacitance , the capacitor must be discharged , otherwise very likely damage the meter ."
FWIW my meter does measure down to a few pf. It also measures higher than 20H but the accuracy declines.
Indeed, discharge a cap before testing it! This is just good practice, regardless of the tester IMHO.
From the eBay post: LCR-T4 ESR Meter Transistor Tester Diode Triode Capacitance SCR Inductance US | eBay
"Description:
Features :
1,2013 latest M328 version of the software ,more functions.Chip: Atmega328
2.128*64 big Backlight LCD display,only 2mA when stand by.
3,Using 9V battery (Not included)
Test ranges:
Inductors, capacitors , diodes, dual diode , mos, transistor, SCR , the regulator, LED tube , ESR,
Resistance,Adjustable potentiometer
Resistance :0.1 ohm resolution, maximum 50M ohm
Capacitor :25pf -100,000 uf
Inductors : 0.01mh-20H
Function:
1:Automatic detection of NPN and PNP transistors, n-channel and p-channel MOSFET,
diode (including double diode), thyristor, transistor, resistor and capacitor and other components
2: Automatic test the pin of a component, and display on the LCD
3:Can detect the transistor, MOSFET protection diode amplification coefficient
and the base to determine the emitter transistor forward biased voltage
4: Measure the gate and gate capacitance of the MOSFET threshold voltage
5:Use 12864 liquid crystal display with green backlight
Specifications: For you reference
1,One -button operation, automatic shutdown .
2,Only 20nA shutdown current.
3,Automatically detect NPN, PNP bipolar transistors , N -channel and P -channel MOS FET,
JFET , diodes , two diodes, thyristors small power unidirectional and bidirectional thyristor.
4,Automatic identification components pin arrangement .
5,Measuring bipolar transistor current amplification factor and base - emitter threshold voltage.
6,Via the base - emitter threshold voltage and high current amplification factor to identify Darlington transistors.
7,Can detect bipolar transistors and MOS transistors protection diodes.
8,Measuring the gate MOS FET threshold voltage and the gate capacitance.
9,Can simultaneously measure two resistors and resistor symbol is displayed.
Displayed on the right with a decimal value of 4 .
Resistance symbol on both sides shows the pin number.
So you can measure the potentiometer.
If the potentiometer wiper is not transferred to an extreme position ,
we can distinguish the middle and both ends of the pin.
10,Resistance measurement resolution is 0.1 ohms , 50M ohms can be measured .
11,Can measure capacitanceCan measure capacitance of 30pF-100mF , resolution 1pF.
12.2uF more capacitors can simultaneously measure the equivalent series resistance ESR values.
The two can be displayed with a decimal value , resolution 0.01 ohms.
13,Can be in the correct order and the diode symbol display two diodes , and gives the diode forward voltage.
14.LED is detected as a diode forward voltage higher . Combo of the LED is identified as two diodes.
15,Eeverse breakdown voltage is less than 4.5V Zener diode can be identified.
16,Can measure a single diode reverse capacitance.
If the bipolar transistor connected to the base and collector or emitter of a pin ,
it can measure the collector or emitter junction reverse capacitance .
18 can be obtained with a single measurement rectifier bridge connection.
Notice: Before measuring capacitance , the capacitor must be discharged , otherwise very likely damage the meter ."
FWIW my meter does measure down to a few pf. It also measures higher than 20H but the accuracy declines.
My tester arrived and works.
I tried it on a few JFETs and it correctly identified all of them as N-JFETS and gave me two values - I in mA and Vgs in V.
Here are the values for the trannies I tested:
BF862B
a1 0.78 0.55
a2 0.75 0.53
a3 0.74 0.53
a4 0.76 0.54
a5 0.68 0.48
2N5485
b1 1.9 1.3
b2 1.7 1.2
b3 1.7 1.2
b4 1.5 1.1
Fake 2SK170
c1 0.87 0.62
c2 0.85 0.6
c3 0.89 0.63
c4 0.84 0.59
c5 0.86 0.6
I'm not sure if these values tell me much, or if these measurements will allow me to match trannies successfully.
I tried it on a few JFETs and it correctly identified all of them as N-JFETS and gave me two values - I in mA and Vgs in V.
Here are the values for the trannies I tested:
BF862B
a1 0.78 0.55
a2 0.75 0.53
a3 0.74 0.53
a4 0.76 0.54
a5 0.68 0.48
2N5485
b1 1.9 1.3
b2 1.7 1.2
b3 1.7 1.2
b4 1.5 1.1
Fake 2SK170
c1 0.87 0.62
c2 0.85 0.6
c3 0.89 0.63
c4 0.84 0.59
c5 0.86 0.6
I'm not sure if these values tell me much, or if these measurements will allow me to match trannies successfully.
I built my own transistor tester many years ago with a number of collector current ranges so that it can be used like a poor mans curve tracer.
It is good for matching output pairs and also has a facility to use an external bench power supply to go as high as a couple of amps for really big transistors.
I also do have one of those modern hand held units but it is not obvious what the collector current it uses.
It is good for matching output pairs and also has a facility to use an external bench power supply to go as high as a couple of amps for really big transistors.
I also do have one of those modern hand held units but it is not obvious what the collector current it uses.
It usually just a few mA.
I found testing a 2n3055 I got silly very high results compared to what the datasheet says it should have.
I do like the component testers as go/no go as they don't care what wire is connected to what lead and the results are instantaneous.
I designed my own USB LC tester. It just uses a comparator oscillator to measure the frequency. The oscillation time is sent to the PC via USB and the PC does the maths on it to work out l or c value.
I also designed a USB PC oscilloscope. It has half a dozen voltage ranges and few frequency ranges. Works very well for just a few pounds.
My home made unit dates to the 1970s and the base current is monitored and a calculator is used with the fixed collector current to get HFE in the range 2. 5 10 50 and 100 ma or the collector can be fed from a bench PSU for higher values until the internal base current runs out. A good TO3 well go up to a couple of amps.
I have two.
One was a Peak unit which was about £50. It lets you connect any way you want and sorts outs the connections for you.
The other semiconductor analyser I bought for about £60 which also does breakdown voltage testing but you have to connect to specific leads.
There seems to be loads on ebay for a few pounds but I don't know how good they are.
Mine set me back a whopping $15! Loads of projects have turned out just fine with it.
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