Category: project

A beefy electronic load (#P4F2)

Hello again!

I’ve been asked: What do you do with this electronic load thing? Well, I‘ve been using it as a battery torture device, what else could you do with a variable resistance device…

For a crude first step in actually testing my unit and also classifying a newly harvested set of deeply discharged 18650 cells, I slapped together some minimalistic Arduino program and hooked the thing up in parallel to the battery under test. The electronic load was set to 2 Amps with another battery, which was monitored by the Uni-T 203A current clamp. […]

A beefy electronic load (#P4F1)

Well, that was a long week…actually, it was a fortnight ;)

Here we go!

(the alignment of images really sucks when placed near the header of the post – thanks WordPress!)

So this puppy was manufactured by my new friends over at OSH Park (ordinary order, no extras) and I think I hit the express jackpot. I registered on June 8th and submitted my files – three hours later (1 AM my time on Friday) I already got notice of the panel assignment. Maybe the small size of 54mm x 31mm (2.1″ by 1.2″ for the Yankees out there) just made a perfect fit on the remaining board size and they sent it straight to production ;) As OSH Park charges 5 dollars per square inch of board area (for three units!), these were 12.75 USD including the free standard shipping. […]

A beefy electronic load (#P4)

This is a ranty introduction to the electronic load project – photos, circuits and more will be available in part 2 next week!

So…I’ve been torturing power supplies (and to a lesser extend: batteries) for ages. Usually to check their health status by comparing the current peak performance to the claimed values in the datasheet. Once you see voltage rails dropping where they should not, it’s time for a replacement of the unit, or in case of specialized PSUs, for a swap of the electrolytic caps.

But the crudity of my testing always bothered me – hooking up power resistors, measuring voltage and current, manually connecting and disconnecting the DUT, never hitting exact performance figures because of the limited selection of torture devices I had around. […]

Lenovo Thinkpad R400 LED Display backlight fix (#P3)

Yes, it’s running in the “projects” category, as “quick and dirty weekend fixes” isn’t available yet :mrgreen:

While I was hosting my brother, he casually asked me when I will fix his display. Umm…what?
Turns out, his Lenovo R400 was showing vertical stripes again. Like these:

(jup, stolen from some Apple customer help page – I didn’t take a photo at the time. I guess the bug is a watermark, isn’t it?)

I’ve already seen and kind-of fixed that on my visit shortly before Christmas last year, when I basically had no tools available. […]

Palladium LA-1000 pre-amp and Revox Evolution stereo system (#P2)

Well, this weekend I’ve been busy replacing dead and leaked caps from something not too Wan-Hung-Lo-ish…a Palladium LA-1000 pre-amp (“Vorverstärker”) back from the 80’s. These are still sold for absurd amounts of money (just like the Revox described down below), so I decided it’s worth a shot. Details on that thing are scarce, and so I’d like to post the cap list in case someone also needs replacements for their dripping electron containers.

Type	Voltage	Count	Reichelt ###	Price	Total	
1µ0	50V	1	RAD FC 1,0/50	0,15 €	0,15 €	
3µ3	50V	1	RAD FC 3,3/50	0,10 €	0,10 €	
4µ7	35V	4	TON 4,7/63	0,39 €	1,56 €	< -- bipolar type!
10µ	16V	2	RAD FC 10/50	0,08 €	0,16 €	
10µ	35V	1	RAD FC 10/50	0,08 €	0,08 €	
22µ	25V	2	RAD FR 22/50	0,06 €	0,12 €	
22µ	50V	1	RAD FR 22/50	0,06 €	0,06 €	
47µ	50V	6	RAD LXZ 50/47	0,09 €	0,54 €	
100µ	16V	2	RAD FR 100/16	0,06 €	0,12 €	
100µ	35V	2	RAD FR 100/50	0,13 €	0,26 €	
100µ	50V	3	RAD FR 100/50	0,13 €	0,39 €	
220µ	10V	2	RAD FR 220/16	0,11 €	0,22 €	
220µ	25V	1	RAD FR 220/35	0,12 €	0,12 €	
220µ	35V	2	RAD FR 220/35	0,12 €	0,24 €	
330µ	35V	1	RAD FR 330/50	0,48 €	0,48 €	
1000µ	50V	5	RAD FR 1.000/50	0,99 €	4,95 €	

You'll notice some caps are binned together, mostly because there are e.g.


7 decade thumbwheel resistor box (project #P1)

A while ago, I wrote articles about a bargain SMD resistor set (WHL #10 ) as well as some thumbwheel switches (WHL #11). Let’s start fresh in 2017 and present the final box :)

As already shown in the thumbwheel post, the initial resistor placement wasn’t perfect. I fiddled some more and I got a case and nice 4mm banana plugs for it. First, let’s see the final measurement results, done with a calibrated Keithley 2700 6 1/2 digit DMM in 4-Wire (Kelvin) mode.

Original performance:

Final performance:

Yep, the 1Ω data point still violates the 1%/10000ppm spec (1,9%). […]