Cap reformer (to 300+V) ...for 50p

[Cre8anet]

A neat little project... a reformer for vintage caps, simply stripped the board out of a Charity shop camera (readily available).

The best thing is it's an incredibly self contained project. I've done one whilst sitting in the swimming pool coffee-shop whilst my son is swimming, and onother whilst watching Garrow's Law on telly. Notes below if you fancy a go.

Reforms caps nicely with a satisfying neon glow at about 280v. Just had to express my 50p's worth of satisfaction and share the success.

Best,

Dave

Most of us probably have a favoured way of doing this properly (maybe just a supply and resistor)... but for those who don't have a safe 300v supply ...and who like fun of getting something neat from nothing (like me):

1. choose a cheapie camera with a flash and flash-ready-indicator.
2. strip down the camera and lay out the innards (put 330v cap in a spot to itself to avoid shocks)
3. locate the charger board (usually a wee transformer visible)
4. add the batteries and switch-on (or short the "on" switch)
5. usually the charge switch is by now, disassembled, so you may need to short the right contacts.
TOP TIP: sometimes takes a bit of finding. It can help to strap a multimeter to the 330v cap, so you can see when a bit of charge starts flowing in!
6. check the unit still charges to 300+
7. locate and mark the other 2 important wires: those to snapshot button;
8. remove other wires to other boards 1 by 1, checking all still charges OK

From most cameras you've now got one small HT board, with pairs of wires going to each of:
- battery compartment (may need taping up but mine worked OK)
- flash (3-wires)
- 330v Cap
- charge switch (mine just flying leads now)
- snapshot switch (ditto)

Finally, box-up and fit flying leads from 330v cap to your test-cap - I prefer to add a 33k current limit resistor in the +lead.

Suggestions/Variations:
- Swap battery compartment for psu;
- add an "on" switch
- add a charge-current meter (5ma?) - this is advisable, so you can see bad caps that are not reforming or not holding charge.
- you will probably want to remove the 330V cap (nice one for the bit-box) and replace with a lower value - say 20u at 450v.

You can leave-in the flash-tester - this comes free as a way of really checking charge is stored in your cap (but beware stressing old caps with rapid discharge. Also values over 100u as most flashers don't like so much charge.)

Time taken after switching-off for the neon to go off gives you an estimated indication of how well cap is holding charge (you'll need to calibrate yours).

The best thing is it's an incredibly self contained project. I've done one whilst sitting in the swimming pool coffee-shop whilst my son is swimming, and onother whilst watching Garrow's Law on telly.

Reforms caps nicely with a satisfying neon glow at about 280v.

Just had to express my 50p's worth of satisfaction and share the success.

Best, Dave
NOTE: This is not a pro-reformer, many of which tell you useful stuff about the cap being reformed. Also, it doesn't guarantee against undesirably high reforming currents, but in my tests, most of these devices can't supply over 5mA.

[tis your junk]

Apart from the obvious question of, did this come to you in a flash?

I would however, be interested to as to how you first thought of this?

In the meantime I'll keep my eyes open for suitable cameras.

TYJ

[Baggrus]

Great idea.. I need to reform the main smoothers in my Laney amp before I power it up for it's once every couple of years warm up.. it's been sitting for 7 years this time.. I forgot about it buried under the stairs.

I have a couple of surplus plastic "nearly but not quite" disposable cameras.. which are I would guess also an excellent source of parts for a project like this?

[Cre8anet]

Yes, the caps, at least are handy. Hope you get your amp going, but note some have quite a bit higher B+ (450+) so it could still get a jolt. Still getting to 300V is a start.

You may want to avoid the modern models of camera. Some have "anti-red-eye" feature. These have messy control logic to flicker the lamp before the main flash. (May not be a showstopper to achieving a good charge but the logic may get in your way a bit!)

I'll try to post up some pics.

Dave

[Cre8anet]

...some pics of mini-reformer you could end up with

The yellow and green wires are the flash-on-switch leads, shorted as a test.

Black wires are to the "fire" (snap-shot) button.

The orange lead tells the rest of the camera that the flash has fire (I think) hence unused here.

Best,

Dave
P.S. Hope your neon comes-on!

[Boom]

Originally Posted by Cre8anet

The orange lead tells the rest of the camera that the flash has fire (I think)

For a slave maybe?

[Baggrus]

Thanks very much for the info. I will get to it when I get moved somewhere else.. No way am I ditching a Laney session50 mk2 (my old stage amp) for peanuts.. the last one I saw (not working and obviously got at) went recently on ebay for £225

The main smoothers are made of stern stuff in the Laneys from '67 .. never had to replace one.. TCC red label . I'll find my junk throwaway cameras (2 of them somewhere) while doing the house clearance and report back soon. They aren't going to have any clever electronics.. just a neon, a flash, a bit of jiggery and a cap I would guess.. probably won't even have to supply the battery.

[davegsm82]

For the record, disposable camera's (24exp) can be had from Poundland that contain a basic but functional flash.

As a bonus, you can cover the lens with the flash off, and trigger the shutter until you run out the film. Once you dismantle the camera then the film will be already wound BACK into the canister. At which point it can be re-used.

Dave.

[G8HQP Dave]

Just a small point: normal electrolytics don't like being discharged via a short circuit or small resistance. If it happens too often their life is shortened. Camera caps are special versions designed to cope with quick discharge. I would guess that as a rough guide the discharge current (one off) should not be higher than a few times the ripple current rating (repetitive).

[Baggrus]

I always discharge large caps (especially 1960's vintage) through a 50k resistor on croc clips.. as I was taught to do many years back. Takes them down nice and gentle. Unless I get the shakes.. then it tends to be skin resistance https://www.vintage-radio.net/forum/...milies/eek.gif