Panel Voltmeters

the reason for the lower set of outputs is that it is not easy to regulate pervectly at say five volts, on a supply capable of sixty.

What's more it might come in handy.

Marlin Jones

----- Regards, Carl Ijames

I went looking into these at Digikey and almost had a heart attack. what I want if a four digit reading voltmeter. I will scale it myself and take care of all calibration, I just need it to read, like the core of a DV?M. I can supply my own resistve divider and feed it whatever it want within reason,

digit jobs will be good enough.

I would really rather have nice big LEDs for the output, power is no problem. ust tell me how much volts to put where and what kinda power you like to eat, done deal.

so these panel meters I see at Digikey, which is where I go for shit like this instinctively, says about forty bucks a piece ! No way.

I do not mean I do not bleieve their website, and that that's what they charge, I say at that price they ain't going into my project. I need four of them per unit. That is simply too much. I do not need alot of ranges or any of that shit. I do not need ten megohm input. While there are limits, like it cannot be ten ohms for exzample, I do not have to worry about that. I don't care if it is only one kilohm, but then I don't need to dissipate that three or four watts at 60 volts... That's all I care. I do not want to build a furnace.

The project is a bench power supply of my dreams. You might want one once I get done with the prototype and know it works well. Iron out the inevitable bugs n shit. going to build two of them to start, after that I think I am going to grab a sheelmetal brake and make some chassis'. See what kind of power transformers I can get at ESI, which is almost local. I just want a power supply with ALOT more output than most.

I am seeing like $300 for little wimpy ones that wouldn't even run a car tape deck. Well we are talking plus and minus 60 volts up to about five amps. Tracking plus and minus when selected. Also, a generator that gives at least square waves so you can drive things, possibly more waveformes later. Filnalize the original design first or course.

Also a lower set of outputs, probably about the same but only up to maybe 15 volts, an amp or so. thos will probably just track and not even have a meter, but markings on the control. you need sub mV regulation, put it in your project. I alkso figure about a 1 mHz oscillator and a divider chain so square waves are available at vartious frequencies, and a switch selects the frequency fed to an amplifier that will put out actual power to drive even a transformer in a power supply.

That part comes later. This happens a step at a time and I just leave roomn on the chassis for more components.

So, the regulation of the power supply itself will of course be chopped. I am figuring the control set. Current limiting, well you can short the output and read the ammeter if you want, but it will more likely not be continuously variable. I see no need for that. you cannot use things like this as a load for a single ended amp beecaause of all the capacitance, so why they hell would anyone need that ? I think a switch would work, 10 mA,

If anyone sees a need for having it continuously variable, please tell me why. Seriously, because you mighht just convince me and I'll put it in. And then you might be more likely to buy one.

Anyway, the point of all this at this time, is that I ntend these to be quality construction and design. Overbuilt. I WANT the people who buy them to take them apart and see what they got. So I want to put the moiney into quality components, not $160 worth of panel meters that should cost about six bucks.

Tell you this, Harbor Freight and them sell little cheapo DVMs for about five bucks. I would hate to just up and use them, but I am not looking for something with 0.000000000 % accuracy here. Get me within a hundredth of a

just not at forty bucks apiece.

Firstly, one would hope the quality would be at least 3 orders of magnitude better than your spelling and word use. Seems you found a cheap DVM .. err .. panel meter, just happens to be in a case and selectable ranges; go for it.

Oh? "Easier" to regulate 5V within (say) 1mV than 60V within 1mV. Source voltage independent within reason.

Do a search on Ebay for "blue led voltmeter" - 2.5 digit panel meters are selling for ~$1.50, 3.5 digits are about $7.

Direct from our friends in Gungzhou, China.

Hmmm. I find this :

Anyone ever deal with them ? They seem to have good prices.

I do not ned a Mazerati to go to the beer store. I see prices like five bucks for these and I like it.

There is one problem, I would like it to read in one range all the way from one volt to like 99. There is actually one I noticed ont eh site there but it is inmput powered and as such cannot measure below 4.5 volts. No good.

But unless someone tells me that p[lace is shit, I guess I will explore there. Digikey's prices on these things were completely pribitive.

Check Amazon

and this one 0-99V, 4.5-30V power supply

( watch the wrap )

Stuff still comes from China. But you are dealing with Amazon if you dont like aliexpress

Understood. I cannot even think of a totally domestic product. Even if I do n't use ICs, half of the transistors will be made elsewhere, and if not the m the resistors, capacitors, who knows. Your chevy has either Chinese or Ge rman fuel injectors in it. there is nothing I can do about this. It will be put together here. I will use surplus parts for the first few. If it goes, then I will get to the new stuff and ordering it and whatevr. I just want to get the design down. First.

Oh, thanks for those links. they look a lot closer to what I need.

Variable current limit is really handy for those all those unplanned times you end up using the power supply for battery charging. Sometimes I reckon my bench psus are used more for charging than anything else. Electro-plating experiments is another possibility. If you can do switched current limit might as well go one step further and go fully variable (and metered of course).

piglet

Try Aliexpress.com Cheap Chinese and with careful buying you can make out well. They use an escrow account deal where they hold the payment until you receive the goods. I got a bunch of thermoelectric modules there for about 20 percent of what they cost stateside and they're good.

I've got the harbor freight volt meters, a pair, and they are good if not to sturdy however the probes are useless with near two ohms between them on the ohms scale.

I've done 20+ deals with aliexpress - they're a portal not a dealer. Use their payment escrow service and if your stuff doesn't arrive, doesn't work or isn't as-described, and you get your money back. Yes, I had to test this once - I suspect Australia Post was to blame. Everything else was quick, cheap and arrived as-described.

No reason not to use aliexpress - they're just an umbrella like Amazon but about 7x bigger, based on recent estimates.

I've been waiting for a need for these lately:

Clifford Heath

There's a cute way to float the supplies, bottom of this page:

Cheers, James Arthur

Ebay is your friend :)

Ebay is your friend !!!!

All sells a LED meter for $15 and an LCD for $7. I don't know if they are any good or not; just that they exist.

Standard disclaimers apply: I don't get money or other consideration from any companies mentioned.

Matt Roberds

power supply.

jamie

Thanks. Now I got options.

now these that say "common ground", that means I do not need a floating sup ply ? If so great, but how does it do negative readings then ? Other questi on, I intend to use a couple of them as current meters. Because of the natu re of the design, which can be split supply (well is) but can be used as a single supply, I am going to have to sense current on the hot side, not the ground side. this is inevitable with my intended design.

So I shold get the floating supply ones for the current and deal with it, a nd use the common ground ones for the voltage ?

Seems logical really. And for that littl nine volts they need, I can just g et an elcheapo transformer with a bunch of secondaries. Regulation will be simple because it is not like they have solenoids and shit, or an audio out put stage. The current drain is probabyl almost constant, only going high w hen it reads 88.88 volts or whatever.

Just kincking some things out there. Taking all opinions, bad, goopd or wha tever.

Thanks.