TEA time, in multiple senses.
I've been looking for a Power Designs 2020 for a little while. The brushed ali front panel looks so pornographic, and the thought of being able to set a low noise PSU in 1mV steps is too much to resist. Proper knobs
and digital - what more could I
possibly want?
The first picture shows the fleabay advert. Knobs missing and a bit suspicious that only the front panel is shown, but at least the voltmeter matches the dials. Bought it for £8 (+£50 P&GSP
), about the same as they cost here unpowered up.
The second picture shows it as it arrived. Not surprised about the case
Checked it was working using a variac set to 115V. (Me a pessimist?)
Rewired it for 240V; back to the "good" old days of unsoldering/resoldering transformer primary windings.
Tweaked the internal zero/cal trimpots. Well, I say trimpots, but they are mounted on the case and have locknuts
Well, what else would you use with an LM399 voltage reference?
Everything works beautifully, and it is certainly accurate enough to calibrate 3.5 digit DVMs.
The final picture shows it after tarting up with car spray and a couple of knobs I've had lying around since the 80s. I will deem it evidence that hoarding
is worthwhile, cough.
Well satisfied. Now there's absolutely no reason to keep the Farnell, just in case.
EDIT: forgot to point out that the indicators are neons (not LEDs), and they flash to indicate an overload. There's something
homely about neons.
Although you can dial up voltages in 1mV steps, the 1mV vernier pot allows voltages to be tweaked to microvolt levels. Once set at, say 100mV, the value stays rock solid at 0.100000V, as measured on an HP DVM with 1uV resolution. In contrast, eyeballing my Tenma PSU gives 50uVpp variations.
There's somethiing
just right about these PSUs;
definitely a keeper.