Matchmaking

I recapped an old Dell power supply, as it has some useful voltages (-12, +12, +5, +3.3) and was more than enough powerful (160W) for most of the projects I do. Added a small load to the +5 rail and the voltages stabilised, that’s the light bulb.. spent a bit of time and built up matching circuit on Veroboard.

messy

Initial testing was good, so tidied things up a little.

board

Set about measuring transistors to see the Vbe of each. Matching at 72F to within 2mV.

measuring

Did 100 of them, they are surprisingly close (all within about 5mV) so I have more matched and/or similar pairs than I thought! That’s good, means all the transistors installed can be identical.

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