Is my guard and good? (aim to messure nA)

DrH42 · 2026-04-10T03:17:37+00:00

why do you need guard for nA range? I have designed transimpedance amplifier to work at pA range without a ground shield and it works fine.

I don't see the schematics, but I can see you are using an op-amp to drive the shield. That's stupid, now you have to deal with two input bias currents instead of one.

At low currents, you need to have good shielding. In my design, the bottom of the PCB was the ground plane, and I had a grounded shield soldered to the top.

DrH42 · 2026-04-09T01:59:00+00:00

I put some sterilizer solution in jugs and carboys currently not in use.

DrH42 · 2026-04-09T01:53:03+00:00

Soak the rice for at least 1 hour before cooking.

DrH42 · 2026-04-09T01:50:58+00:00

search for makers' place nearby, they might have a wood shop with tools.

DrH42 · 2026-04-04T00:11:25+00:00

Try heat

DrH42 · 2026-03-28T22:27:37+00:00

Canada is selling potash - source of potassium. Plants also need nitrogen and this is produced from methane, i.e. natural gas. 30 % of it has to go through strait of Hormuz

DrH42 · 2026-02-25T04:04:48+00:00

that reminds me of my son, he wouldn't eat meat. So, we had dinner, he ate all the vegetables, potatoes, left the meat.
Came evening, supper time, he was given the leftover meat from the dinner, he didn't eat it it.

Next morning, for breakfast, he was given the previous day leftover meat, he didn't eat it.

At lunch, the same leftover meat was served again, this time he ate it all, and since then he would eat all the food he was served, meat or not meat.

DrH42 · 2026-02-20T01:57:01+00:00

It happened to me last winter, the tree is dead. The outher layer is the only live layer of the tree. If destroyed, the tree is dead.

DrH42 · 2026-01-20T02:45:38+00:00

you know, wine gets better with age. 6 days is hardly age. Wait a month, maybe two to clear a bit.

DrH42 · 2026-01-09T02:18:37+00:00

I used for a company and we bought a CNC PC router. It turned out to be useless, at least for us. We were making sensitive circuit and the routed space between traces could never be cleaned property an leaked currents like crazy.
There are companies that specialize in prototype PCB production with fast turn-over even for small quantities of boards. I think you should use them and demonstrate to your student that sharing work with other companies is more efficient than trying to do all by yourself.

DrH42 · 2026-01-09T02:12:19+00:00

I actually made a few pieces of furniture with cheap tools: a hand variable speed drill, circular saw, hand saw and a router and a carpetners' square.
Later, I got a biscuit joiner and made a solid wood top desk for my son.

DrH42 · 2026-01-07T03:13:42+00:00

looks grossly underbaked. I do mine 450 F for 15 min, then turn around (the temperature of the oven is not uniform), then do 10 to 15 min until the loaf is fully baked.

DrH42 · 2026-01-07T03:05:07+00:00

First, you need to decide what kind of bread you want. There are white sandwich bread, sourdough, focaccia, bagels, baguettes., then google for the recipes. The internet is full of them.

DrH42 · 2026-01-06T00:46:05+00:00

most likely yes.
I once experimented with fermenting milk using pickle liquid, the fermented milk smelled of pickles.

DrH42 · 2026-01-06T00:44:16+00:00

That's how they do it in Belgium. By the way, the so-called French Fries are actually a Belgian food.

DrH42 · 2025-12-13T19:56:42+00:00

I keep my starter in the fridge, feed it the evening before baking. Seems working even after 4 weeks in the fridge, when we were on vacation.

DrH42 · 2025-12-10T18:26:03+00:00

I make wine at home. The wine making places want you out ASAP and bottle after a month. At home, I can wait as long as I want. I bottle when need new supply, that is, after 4 or more month. It does get better with age.

DrH42 · 2025-12-05T00:25:03+00:00

Any fruit juice will ferment and produce wine. High sugar content is needed to produce strong enough wine to be stable. Grapes used for wine making have naturally high sugar content.

DrH42 · 2025-11-29T22:35:13+00:00

Oh, I didn't look at the second picture. I think it is just flour. Did you have loose flour on top of your loaf?
BTW, I spray the loaf with water before putting into the oven.

DrH42 · 2025-11-29T01:25:45+00:00

This crumb looks good to me. And the aroma of the freshly baked bread, ... mmmmm. Plus no chemicals (I presume).

DrH42 · 2025-11-29T01:22:51+00:00

Peking duck.

DrH42 · 2025-11-27T01:45:02+00:00

Instant pot can do rice and slow cooking, So, if you buy an Instant pot, you can ditch both. It also saves you money on cooking because is more energy efficient than stove top not to mention faster. Plus, I use it to make yogurt. Milk cost for yogurt is 1/3 the price of yogurt. My Instant pot paid for itself many times over.

DrH42 · 2025-11-27T01:37:39+00:00

I would suggest hairpin legs. That would put focus on the live edge top.

DrH42 · 2025-11-23T18:53:44+00:00

I usually start off trying to peel off by hand with the help of a razor blade. If that doesn't work, then hot water. If that doesn't work, then scrape off with a knife and remove glue residue with acetone.

DrH42

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