Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Are you sure the heater isn't supposed to be left floating? You could experiment with an additional transformer to power your DC-DC converter and see if the problem goes away.

Considering how small your current requirement is, you could easily hand wind a 1:1 toroidal transformer to power from the heater transformer; or even a small AF DC-blocking transformer would probably work. If the DC-DC converter doesn't want to play nicely, a simple zener diode regulator circuit, or like I suggested earlier, a voltage divider across the output of something like an AM1117-3.3 linear which should keep your overall current draw down to a few milliamps.

mnem
Bees do not taste like honey.

Problem solved, it was the full wave rectification, replace that with a single diode for half wave, followed by that 1000uF 25v cap and bingo, everything works and not a hint of volt drop anywhere, all rail AC and DC rock solid, now to transfer it from bread board to pcb and install it.

Successfully transferred the circuit from breadboard to PCB and installed, tested and calibrated, works like a charm, no more worries about battery leakage, especially as its a piece of equipment that does not get used all that often and judging by the state of some of them offered for sale on eBay is pretty the same for most owners. This one wont be suffering from battery corrosion in the future 

You can just about read the heater voltage on the HP 3466A (5.385vac) in the background while the F27 (1.504vdc) on the left reads the output from the DC to DC converter and the F27 (6.66vdc) on the right reads the half wave smoothed DC input to DC to DC converter.

Winner winner.... reading VAC, VDC and resistance all on the same jacks without having change input jacks just can't use the original Heathkit RF probe which would shared the DC i/4" socket with the DCV input, and as I don't have a probe, it would be safer to convert to a more conventional way of using a multimeter.

If anyone else is interested in doing a similar thing, the schematic below is a copy of the hand drawn battery replacement that Heathkit engineers designed and fitted to a lot of meters in the factory prior to shipping according an ex Heathkit employee. I did not use this method however, just dc to dc converter 5-6V in and 1.5v out and fed it with power taken from the same source as the alleged Heathkit drawing via a IN4001 and 1000uF 25VDC cap.


   

Awesome! I figured you'd already tried 1/2 wave and it was too noisy, so that was why the bridge. Simplify! 

Oh dear so sorry to hear that, have you informed them of your disappointment, maybe a partial refund or something might help make you feel better about it? I have to say that I'm extremely pleased with my 2, their condidtion is as if I had brought them new in sealed cartons and just removed the plastic bag for the first time.

No, but I don't think it makes much of a difference. Their ad stated it was used and showed a yellowed example and that's what I got. Plus that it's not the money, I just want a counter in a decent condition. Even giving me back my money thrice over won't help that. Though shipping has taken ages, they've been very helpful otherwise. I don't want to complain about something they didn't even do wrong. They seem to be good people.

Considering all the luck you lot had with your pristine specimens, I had hoped for something better. Bugger. I'll go mumble bad words to myself in a corner now.

Guess I'll get to try the retrobright unyellowing technique.

Post a photo here anyway.

Yeah, we're all curious. Curious to know if it works properly as well.


mnem
I'm wearing pants!

[med6753]

Cheap resistor decade box, that i can't buy, here, https://www.ebay.com/itm/Ohmite-OHM-Ranger-Stock-3420-pre-owned-used-untested/132487515267?_trksid=p2485497.m4902.l9144

Why can't you buy it then?

The wallet said that if bought one more thing this month i would be sleeping in the snow, what can i say? After seeing the bill if i win this nixie tube bench meter i believe her. 

I'm so glad that I am the wallet and I answer to NO ONE 

You know sometimes its good to answer to someone, it does have its advantages as well. 

She has her own place. I have mine. She spends her money on clothes and shoes. I spend mine on TEA. No conflicts. No questions. Life is good. 

Until somebody wants to have a closer relationship and then the shit hits the fan and suddenly TEA gets more complicated as a result 

Of course there's always that possibility but as of right now there's no fan.  We've been together for 7 years. Neither are interested in getting married. Both of us have been there, done that. We enjoy our time together as well as apart. It works for us and I don't see it changing (fingers crossed). 

[AF6LJ]

Successfully transferred the circuit from breadboard to PCB and installed, tested and calibrated, works like a charm, no more worries about battery leakage, especially as its a piece of equipment that does not get used all that often and judging by the state of some of them offered for sale on eBay is pretty the same for most owners. This one wont be suffering from battery corrosion in the future 

You can just about read the heater voltage on the HP 3466A (5.385vac) in the background while the F27 (1.504vdc) on the left reads the output from the DC to DC converter and the F27 (6.66vdc) on the right reads the half wave smoothed DC input to DC to DC converter.

Winner winner.... reading VAC, VDC and resistance all on the same jacks without having change input jacks just can't use the original Heathkit RF probe which would shared the DC i/4" socket with the DCV input, and as I don't have a probe, it would be safer to convert to a more conventional way of using a multimeter.

If anyone else is interested in doing a similar thing, the schematic below is a copy of the hand drawn battery replacement that Heathkit engineers designed and fitted to a lot of meters in the factory prior to shipping according an ex Heathkit employee. I did not use this method however, just dc to dc converter 5-6V in and 1.5v out and fed it with power taken from the same source as the alleged Heathkit drawing via a IN4001 and 1000uF 25VDC cap.

Nice!
I need to do that to my IM-18 (Heathkit) and my RCA VoltOhmist.

[Specmaster]

Awesome! I figured you'd already tried 1/2 wave and it was too noisy, so that was why the bridge. Simplify! 

mnem
I'm wearing pants!

No,I hadn't, I just assumed that it would be better with a full wave so designed it that way  I suppose that the bridge rectifier was introducing another return path for the DC to saturate the heater winding? 

[Specmaster]

My cheap Chinese ring light for the microscope arrived today. It wasn't designed to fit this microscope but I thought that mounting screws looked long enough to grip it, and the fact it only cost me 1p plus postage, thanks ebay, nobody bid against me 

Well here it is mounted on and it works really well along with a couple of screen grabs, one with the built in ring light and the other with the built in switched off and the new one on, can you tell the difference 







Note to self, must clean the fingerprints off the screen.
 

[mnementh]

Awesome! I figured you'd already tried 1/2 wave and it was too noisy, so that was why the bridge. Simplify! 

mnem
I'm wearing pants!

No,I hadn't, I just assumed that it would be better with a full wave so designed it that way  I suppose that the bridge rectifier was introducing another return path for the DC to saturate the heater winding? 

Well, a lot of valve circuits keep the heater floating; I suspect possibly due to potential return path within the tube. Without the meter schematic in front of me, not sure what other return paths, but I see a lot of potential there with a differential amplifier circuit, just going from memory. 

At least it's not a FET version... each of these trial & error experiments you've engaged in would likely come with magic smoke from one or more of them.


mnem
*tzzzzt*

[Specmaster]

Nice!
I need to do that to my IM-18 (Heathkit) and my RCA VoltOhmist.

I just checked and your IM-18 is basically the same as my V-7AU except mine has 2 x 4mm banana jacks for common and ACV so the schematic is very similar and I also found this video which covers your meter.

[beanflying]

I really hate to see gear damaged like that.. The person who packed the box should be packed up and sent across country like that.

Current offer for the piss poor packaging job is $100USD refund. Should cover some metalwork $ toward tidying up the cast handle 

[AF6LJ]

I really hate to see gear damaged like that.. The person who packed the box should be packed up and sent across country like that.

Current offer for the piss poor packaging job is $100USD refund. Should cover some metalwork $ toward tidying up the cast handle 

I would ask for a 35% refund.

[beanflying]

It was a bit under $300 USD with shipping. So already there.

The next person who sooks about the auto ranging speed of the 121GW should be forced to watch a video of the 20-30 warm up and then taking a reading with this 

Just coming back under 10mV at 30 minutes 

10V range is very close 

After 3 hours warm up one LSD off the 34401a and has been holding for over 30 minutes - 

[bitseeker]

At least there are nice, warm, glowy digits to admire while waiting.

[beanflying]

Very warm 35C degrees plus unlike your likely 35F 

740B has a positive temp co it seems 4 counts up on the Agilent as I open Beer 2 

Mmmmm Refund pending what to buy with it? Test Gear with Nixies, Test Gear with analogue meters, components, food .......

[URI]

TEA stroke me again!   

I came across an Agilent 6063B electronic load in nice and working condition offered on *bay for $208 plus shipping&customs (don't ask for it, it's quite an amount but summed up it's still a very good price for such a device on this side of the Atlantic).
I actually sat in front of my computer for nearly ten minutes having an inner fight whether to give in to buy it or not.
In the end I clicked the buy it now button.
I could not stand it.   

After all, it's a relief to write it here. Feeling better now.*
I'm really hoping for fast shipping..!   

PS: The next temptation has caught me: I can't stop thinking of getting a T12 clone station with OLED -the necessary parts are available on *bay..    (as you know, I don't like to buy on aliexpress an the like)
PPS: *- just noticed, I'm running out of space for all those boat anchors.

[imidis]

Please share photos of goodies when they arrive so I can vicariously live through you. Thanks! 

[bitseeker]

After all, it's a relief to write it here. Feeling better now.*

Very good. That's one of the useful therapies available here in the TEA house.

Please share photos of goodies when they arrive so I can vicariously live through you. Thanks! 

And that's another.

Of course, the latter is more budget-friendly.

[Specmaster]

TEA stroke me again!   

I came across an Agilent 6063B electronic load in nice and working condition offered on *bay for $208 plus shipping&customs (don't ask for it, it's quite an amount but summed up it's still a very good price for such a device on this side of the Atlantic).
I actually sat in front of my computer for nearly ten minutes having an inner fight whether to give in to buy it or not.
In the end I clicked the buy it now button.
I could not stand it.   

After all, it's a relief to write it here. Feeling better now.*
I'm really hoping for fast shipping..!   

PS: The next temptation has caught me: I can't stop thinking of getting a T12 clone station with OLED -the necessary parts are available on *bay..    (as you know, I don't like to buy on aliexpress an the like)
PPS: *- just noticed, I'm running out of space for all those boat anchors.

Well at least the T12 isn't a boat anchor, I expect that in the end you are buying from AliExpress as ebayer is more likely to be a drop shipper. Also of course you'll be paying more for it as well.

[neo]

I make it a rule to have a clear cut spot, or at least an idea for one, before i buy anything. 

[Specmaster]

I make it a rule to have a clear cut spot, or at least an idea for one, before i buy anything. 

That's a good idea, especially if the one you're clearing is a boat anchor, more room for smaller items equals expansion overall [emoji6]

[beanflying]

Ordering a second 11RU to finish racking the underside of a mobile T&M bench next week. Then time to look for full sized rack for 'expansion' 

[BravoV]

Need help from the brotherhood of TEA -> Price of an used Fluke 189

[URI]

After all, it's a relief to write it here. Feeling better now.*

Very good. That's one of the useful therapies available here in the TEA house.

Yeah, it would definitely not be any relief if I told my wife.. 
Glad to be able to share it here. Makes me more comfortable with my TEA.      

Please share photos of goodies when they arrive so I can vicariously live through you. Thanks! 

And that's another.
Of course, the latter is more budget-friendly.

Yes, but always at least somebody has to pay to delight the others..   

@imidis BTW: I will share photos, at least the outside of those goodies that are to arrive. 

[URI]

The next temptation has caught me: I can't stop thinking of getting a T12 clone station with OLED -the necessary parts are available on *bay..    (as you know, I don't like to buy on aliexpress an the like)

Well at least the T12 isn't a boat anchor, I expect that in the end you are buying from AliExpress as ebayer is more likely to be a drop shipper. Also of course you'll be paying more for it as well.

Yep, those little T12-Clone-Boxes will always fit well into those unavoidable gaps between boat anchors.   
We'll see what and where I will be buying from that T12-Clone-Cosmos. Haven't made up my mind yet. Like "ten minutes" or so. 

[mnementh]

I'm waiting for an edge-wise version... you could use them to chink up holes just like a half-brick. 


mnem
Back to the bench*

[Specmaster]

Just use the standard one and stand it on its side, job done.

[Neomys Sapiens]

TEA stroke me again!   

I came across an Agilent 6063B electronic load in nice and working condition ...
In the end I clicked the buy it now button.

I would not call it an boat anchor like some of the posters, but I do not like it very much either!
There are Hoecherl&Hackl, the newer Zentro, Transistor Devices, EA, Schaefer, ET System, Chroma...
and you got the only one with keys only operation. Pesky. That is an instrument where I would insist on having direct acting rotary control. But if you are fine with it, it's a decent grab.

PS: The next temptation has caught me: I can't stop thinking of getting a T12 clone station with OLED -the necessary parts are available on *bay.. 

Ok, I'm now officially baffled (more baffled that a triple baffle muzzle brake) with that craze about those stations. Do you all really think that they are better than Weller AND JBC? WHY?
That is not only directed at you, URI! But I fail to comprehend why a whole bunch of people that have their benches crowded by anything that is solid, nice and precious in T&M gear are collectively on the run for chinese Hakko clones. Is soldering such a lower-ranking activity to you all or what did I miss here?