09-05-2011, 02:12 PM
(08-05-2011, 11:16 AM)Pamphonica Wrote: A while ago I put this device together. It uses constant current to reform caps and I have had a lot of success with it (despite a few negative comments when posted elsewhere!).
Provided to encourage discussion and kick off development ideas, not to trigger debate over "best" methods.
Total cost of bits would be about £20-£30, incl the dvm module. Far less if you have a good bits box.
all the best
Jeremy
Beautifully designed and drawn Jeremy! What software did you use to draw the circuit please? I'm not familar with the IRFBC40, but I've checked the datasheet and see that it's a hefty power MOSFET - 600V, 6 Amps, so it's well in spec in your application. When I was poking around searching for suppliers, I found this firm, which I've not come across before, but they seem to have lots of useful stuff and claim to be the main UK supplier of repair kits for LCD TVs etc. (I didn't check their P&P charges or whether they have minimum order quantities or values):
http://www.ohmsupplies.co.uk/epages/6202...ucts/TRT01
As to the little digital meter modules, who'd have though just a few years ago, that they'd become as cheap or cheaper than analogue movements? Neat idea to switch the meter with shunts to read Voltage and current. The only thing about these meters - certainly the ones that I've come across, is that the supply voltage that powers them must not be derived from the circuit that is beaing measured, but you've catered for that with the 6V winding on the transformer, rectified to provide the 9V for the meter. Some of the meters use a 5V or 12V supply, but that could easily be catered for.
The nice thing about homebrew, is that you can design and build geaer which is simply not avialable at any proce commercially, and over time, it susprosing how so much of what's needed can be found in an ample spares box. EG, a mains transformer from a scrap AC radio would suffice for the transformer, which would be the major expense in this instance.
As to negative comments from critics and sundry pedants, the one common feature they tend to have is that they're reactive rather than proactive - good at finding fault with the efforts of others, but never being creative themselves. And you're right about there being no 'best' or preferred method. The bassic priciple is invariably the same - build up the voltage as leakage current subsides, until the rated voltage of the cap is reached, by which time, hopefully the cap will be reformed, or consigned to the bin!
David
