Author Topic: Test Equipment Anonymous (TEA) group therapy thread (Read 17334022 times)

tautech · « **Reply #25025 on:** February 11, 2019, 07:22:22 am »

Sure, that way of thinking I understand especially if usage is likely to be limited.

Brumby · « **Reply #25026 on:** February 11, 2019, 07:32:21 am »

Quote from: tautech on February 11, 2019, 07:22:22 am

... especially if usage is likely to be limited.

That's the unknown. The intention is there - but once you've had a taste .....................

med6753 · « **Reply #25027 on:** February 11, 2019, 10:12:21 am »

In looking over my DMM clan everyone has been freshly calibrated except the Tek 2465 DMM. That guy has "closed case" calibration and one of the constants it needs is 500VDC. The 500VDC reference is on hold for another DC-DC converter and that won't be ordered until the end of the month with a large planned parts order. So that will have to wait for now.

I have an itch. And it needs to be scratched. Hopefully Invert will ship that 7704 today. That's only thing that's going to relieve this itch. And of course that's going to spark a plug-in buying spree on E-Bay. I've already been out there cruising and planning.

And the Weather Service has posted a Winter Storm Watch for Tuesday into Wednesday. 3rd one this winter. Spring can't come soon enough.

beanflying · « **Reply #25028 on:** February 11, 2019, 11:00:48 am »

500VDC seems fairly common with Electrophoresis power supplies this ones form factor and price isn't to bad eBay auction: #123627519122 Seems to be plenty of similar options that you could tweak a bit. Might be handy to have for Tube playing too.

med6753 · « **Reply #25029 on:** February 11, 2019, 11:28:24 am »

I currently don't have any tube gear except for a VTVM. But if I did a supply like that would definitely come in handy. But for references and calibration I don't need a supply like that because there's almost 0 current draw.

beanflying · « **Reply #25030 on:** February 11, 2019, 11:45:22 am »

Can you do it for less $ with a smaller DC-DC converter with good safety? I still recon you need to jack up the bed and hide a 332 or5 from Inverted under it

med6753 · « **Reply #25031 on:** February 11, 2019, 11:57:44 am »

This is the Inverter card. The one I received last week I dropped on the floor and damaged it. Luckily they are only $15 USD. The 500VDC project requires 2 of them in series. The other one is already built up and supplies a stable and accurate 250VDC.

I'm just waiting until the end of the month to order a replacement.

bd139 · « **Reply #25032 on:** February 11, 2019, 12:08:05 pm »

Just watch out for the total voltage to ground. Some of the cheap ass inverters will flash over if you're not careful or they are made of poo.

med6753 · « **Reply #25033 on:** February 11, 2019, 01:43:43 pm »

Quote from: bd139 on February 11, 2019, 12:08:05 pm

Just watch out for the total voltage to ground. Some of the cheap ass inverters will flash over if you're not careful or they are made of poo.

That's why at this point the reference will be powered by batteries and once built mounted in a plastic case. It will be totally isolated from ground.

bd139 · « **Reply #25034 on:** February 11, 2019, 01:51:33 pm »

Relative ground not earth. If you have to stack about 500V, which you will probably do to get the regulation at that voltage, watch your HV wiring doesn't go near the 0V reference. I had problems with flashover with cheap Chinese devices and wire around 300V. Literally they build it to the line.

Edit: I got 800V out of one stage in a flyback arrangement once. Had a 1KV MOSFET and a not particularly good home wound inductor. First couple of attempts, the inductor lit up like a firework display

med6753 · « **Reply #25035 on:** February 11, 2019, 01:55:50 pm »

Quote from: bd139 on February 11, 2019, 01:51:33 pm

Relative ground not earth. If you have to stack about 500V, which you will probably do to get the regulation at that voltage, watch your HV wiring doesn't go near the 0V reference. I had problems with flashover with cheap Chinese devices and wire around 300V. Literally they build it to the line.

Edit: I got 800V out of one stage in a flyback arrangement once. Had a 1KV MOSFET and a not particularly good home wound inductor. First couple of attempts, the inductor lit up like a firework display

OK, I got what you mean. Dully noted and I'll watch the lead dress as well as I'll insure good head space between the 2 cards.

nixiefreqq · « **Reply #25036 on:** February 11, 2019, 02:03:50 pm »

a picture for neo.

med6753 · « **Reply #25037 on:** February 11, 2019, 02:11:11 pm »

There's an example of good lead dress to keep those HV electrons in their place.

Specmaster · « **Reply #25038 on:** February 11, 2019, 02:11:39 pm »

Quote from: beanflying on February 11, 2019, 11:00:48 am

500VDC seems fairly common with Electrophoresis power supplies this ones form factor and price isn't to bad eBay auction: #123627519122 Seems to be plenty of similar options that you could tweak a bit. Might be handy to have for Tube playing too.

Cor, wish we had psu's at similar prices over this side of the pond, that thing is a steal, snap it up someone

med6753 · « **Reply #25039 on:** February 11, 2019, 02:15:16 pm »

Quote from: Specmaster on February 11, 2019, 02:11:39 pm

Quote from: beanflying on February 11, 2019, 11:00:48 am
500VDC seems fairly common with Electrophoresis power supplies this ones form factor and price isn't to bad eBay auction: #123627519122 Seems to be plenty of similar options that you could tweak a bit. Might be handy to have for Tube playing too.

Cor, wish we had psu's at similar prices over this side of the pond, that thing is a steal, snap it up someone

They ship to the UK.

(Probably cost more than the supply itself)

Oh yea....and that stupid VAT too!

Specmaster · « **Reply #25040 on:** February 11, 2019, 02:17:58 pm »

My point exactly, the BIN price was what I referring to

That is a really good price.

med6753 · « **Reply #25041 on:** February 11, 2019, 02:21:21 pm »

Quote from: Specmaster on February 11, 2019, 02:17:58 pm

My point exactly, the BIN price was what I referring to That is a really good price.

BIN? What does it stand for.....I assume including shipping and VAT (Value Added Tax)?

Brumby · « **Reply #25042 on:** February 11, 2019, 02:42:12 pm »

BIN = Buy It Now

med6753 · « **Reply #25043 on:** February 11, 2019, 02:46:59 pm »

Quote from: Brumby on February 11, 2019, 02:42:12 pm

BIN = Buy It Now

Oh sorry....not up on E-Bay lingo.

neo · « **Reply #25044 on:** February 11, 2019, 04:29:51 pm »

Well looks like TEA is going to simmer on the back burner a while, my car decided it didn't like the 1000 mile drive and dropped dead shortly after. Here's hoping it CAN be fixed

bd139 · « **Reply #25045 on:** February 11, 2019, 04:38:52 pm »

I know how you feel there. I've been humming and hawing over buying an Elecraft K2 kit. Figured I'd get the car through service and see what the deal is. This morning it ate two tyres, more bodily fluids than I have inside me, new front discs and pads all round. Basically the entire cost of the K2 kit nearly to the bloody penny.

Specmaster · « **Reply #25046 on:** February 11, 2019, 05:30:59 pm »

Was it just a normal car service or did it go in for something specific, either way it's OUCH

Specmaster · « **Reply #25047 on:** February 11, 2019, 05:32:42 pm »

Quote from: neo on February 11, 2019, 04:29:51 pm

Well looks like TEA is going to simmer on the back burner a while, my car decided it didn't like the 1000 mile drive and dropped dead shortly after. Here's hoping it CAN be fixed

I expect it objected to carrying to many boat anchors for 500 miles plus you and dad

bd139 · « **Reply #25048 on:** February 11, 2019, 05:40:23 pm »

Quote from: Specmaster on February 11, 2019, 05:30:59 pm

Was it just a normal car service or did it go in for something specific, either way it's OUCH

Normal service. It was a "full service" interval. I sort of expect this when you buy a second hand car the first time it gets serviced. I also tend to do get everything fixed right away rather than leave it on a warning after a bad experience when I was a kid. I was in my father's old Ford Cortina going round the M25 back when it just opened and one of the wheels came off at 60mph. Shit had to be scraped out of everyone's undies after the following 10 seconds. No one was hurt fortunately.

nixiefreqq · « **Reply #25049 on:** February 11, 2019, 05:54:06 pm »

Quote from: med6753 on February 11, 2019, 02:11:11 pm

There's an example of good lead dress to keep those HV electrons in their place.

really did drop that in there as part of a pm discussion with neo.

purely a coincidence that you guys were talking about hv precaution.

but since it came up. hey neo.....be careful around HV. it really really hurts!


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Author Topic: Test Equipment Anonymous (TEA) group therapy thread (Read 17334022 times)

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