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SMD Test Fixture for the Tektronix 576 Curve Tracer

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I needed to test some AO3400 and AO3401 MOSFETs that I purchased from Aliexpress. I decided to make a little circuit board to test MOSFETs on my Tektronix 576 Curve Tracer.
It is a simple project. I thought it might be useful to other people, I am sharing it here.


Not a lot to say about the schematic.


I made a panel, with mouse bites, so that you get better value from JLCPCB etc.


I made a simplified prototype, using an LPKF c60 circuit board mill.

The prototype was used to check the spacings of the banana plugs.

Gerber files

I have attached the Gerber files if you want to order these board. I suggest that you check the Gerber files carefully. I have not got the PCBs back from manufacturing.



Here are the results from testing the Aliexpress AO3400:


This is the breakdown voltage from Drain to Source. The measured value was 23V. The specification for the AO3400 is 30V.


This is the measured RDSon, the on-state resistance. The resistance is calculated by picking a point on the curve and dividing the voltage by the current at that point. The measured RDSon was 25mV/96mA = 260 m \$\Omega\$. This is much higher than the specification (<28m \$\Omega\$)

At least I got MOSFETs that might be useable in some applications ...


Great idea  :-+

We've been working on something similar for our Tek 577, see attached images.

This utilizes both sides with the banana jacks to allow A/B comparisons and a ZIF socket for leaded devices.

For SMD an additional topside PCB plugs into the base unit pcb with the ZIF socket removed. The SMD DUT are pressed down onto the PCB to make contact with the Lever Arms shown in the paper mockup mounted on the 577. We'll see how well this works later.

We haven't had time to order these PCBs yet, as other pressing needs have surfaced, hopefully will be able to get back to this soon.


mawyatt and the group,

I have attached a file containing the .step files for a single PCB mounted banana jack and the five jack array used for the Tektronix curve tracers.

The zipfile also contains the Fusion 360 models that were used to make the models.


Thanks, we're using the Pomona 72918 banana plug, Mouser 565-72918.

Need to finish up the solder SMD plug-in PCB that plugs into the base PCB like the PCB with the Lever Arm fixture shown.

These 3 PCBs will allow the use of leaded components with the ZIF socket, non-soldered SMD with the Lever Arm Fixture PCB which fits on top of the base PCB (with ZIF removed) and finally smaller soldered SMD PCB which also sits on top of the base PCB (ZIF Removed).

We'll post the design files after we order/get the PCBs and get things assembled and tested. Not sure how well the SMD Lever Arm fixture will work since it's based upon pressure contact of the SMD which likely will be highly variable, but worth a try!!

Regarding your components from AliExpress or eBay, seems it's always a question with components from them. We've had sub-par LM358s, a LM399 that drifts, sub-par TI switch, and other questionable components. Had good results with the usual US suppliers Mouser, Digikey, Newark and even Chinese LCSC.

Edit: Here's the Solderable SMD Fixture, this plugs in by the 16 pin header and mounts on top of the Base PCB which has the Banana Jacks for the Tek 577. The Kelvin feature is utilized to help remove the connector and trace effects. The PCB is small (0.9 by 0.9 inch), so should be relatively cheap.



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