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As a lifelong analog EE, I have built and used many DC power supplies starting with an LM309 5V regulator in the late 60’s. Then on to uA723s, various 3 terminal linears, and many switchers. At Analogic in the late nineties I got to work on Semiconductor ATE equipment. One extreme was the AN/DP8200 VoltBox, a precision 20 bit voltage standard. I was exposed to low power SMUs for semiconductor testing. Then at Teradyne I was an analog EE in their DC instruments group, where we designed serious VIs (voltage-current instrument), DPSs (Device Power Supply) and SMUs for semiconductor and system testing. I have built various DC loads up to 20A, and LED testers up to 50A and 50V. I built a 4 quadrant power-supply and load (PS-Load). Not to mention my many audio amplifiers and Thermo-electric cooler (TEC) controls. I set up the PowerOne hackers blog.

So here it is 2020, and if you want an instrument to do basic semiconductor DC testing, curve tracing or the like, plan to spend $4,000 and up for a new instrument such as a Keithley 2400 Source Meter. You’ll need 2 instruments to drive both the base and collector to test a transistor or other 3-terminal device. Need to test a multi-pin device? Add more instruments if they need to operate at the same time, or a multiplexing system if they can operate in a sequence. Real world applications get very expensive.

I looked at the older Keithley 236/7/8 SMUs, and very much like their capabilities. They can output micro-volts to +/-110V (model 236) or +/- 1100V (model 237). Wide current ranges from 1nA to 100mA full scale, 1A for the Model 238. But these are 30 year old designs and a full 19” rack wide. On Ebay they go for $1,000 or more, depending on condition.”

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