Win a Tenma Power Supply

I've used power supplies such as this for electropolishing. Wrap a cloth around a cathode (such as a copper bar), dip in electrolyte solution, and "paint" spot by spot, re-dipping in electrolyte solution as necessary. See here for one example: https://www.youtube.com/watch?v=T595XvcW8cE

I don't know how I ended up on this website or what you would normally use a standalone power supply for but this thing looks like I could probably get it to make music if I plugged it into my modular synthesizer. It would definitely make for a cool experiment even if I ended up sending overvoltage all through my synth. So yeah, I'd see if I could get it to produce some nice drones or control voltages to make music with it.

In my workplace we have numerous very remote sites that perform very critical functions and equipment failures aren’t an option.

These sites are over 2 solid days (one day without any tarmac roads) drive into the desert from anyone able to perform technical repairs or fault finding. Our equipment is mounted in unventilated steel enclosure in areas that regularly get into the high 40 degrees Celsius, pushing devices to their thermal tolerance limits

To provide redundancy against power failure the equipment at these sites is powered via banks of sealed lead acid batteries

Through trial and failure we have found that modern battery chargers don’t seem to cope well with the climatic conditions where these sites are located and instead we modify power supplies to act as battery chargers.

The supplies we use are intended to be bench power supplies for radio equipment but with a few small tweaks make excellent albeit simplistic battery chargers and despite having almost 100 in the field we’ve never had a failure.

These power supplies are very simple analogue affairs based on a big heavy transformer but sometimes simple is good.

Although the chargers are simple we get excellent battery life.

Not that far removed from the power supplies intended use but thought you might find our solution interesting.

I should say that these are 1940s relays!  And we would try and clean them with switch cleaner first.

It would be great to use for electro-etching metal, ie home made knife etc..

Here is my Idea

Overloaded Geek's Supply:

When ever you are programming, debugging and testing the hardware then every time you might require to turn ON/OFF the power supply after reprogramming and testing cycle. And this repeatedly turning ON/OFF the power supply really drive you crazy especially when things are not working out as you wish.

So in order to make life easier, I will like to convert this analog supply to PC controllable power supply which can be turned ON/OFF by simple keyboards shortcuts and also other setting can be adjusted by the user configurable keyboard shortcuts.

Key Features:

Keyboard shortcuts for everything

• voltage setting
• current setting
• power supply mode setting
• ON/OFF

My electronics tickle trunk had a three inch strip of emery cloth tucked away in some obscure pouch. Burnishing the contacts on 48VDC relays after a spritz of contact cleaner was common in the 70's & 80's. Vacuum tubes were also common:) As electronic became more refined the large surface area on contacts of relays disappeared.

I agree the contact surface of most relays or switches for that matter have very little material to apply the burnishing techniques that work in the past. I do recall being told never burnish contacts that were gold. The surface thickness wouldn't tolerate such a brute force technique.

Sean

I don't recall any vendor solutions that use arching to clean contacts. Arching on contacts is a condition usually avoided.

I have on occasion, rapped the side of a computer hard drive, in the hope the drive will spin up. The solution has yet to work for me. I have seen the rap technique work on vehicle alternators. I suspect in an system administration crisis lore the solution has unstuck a drive. I have yet to find a vendor that supports this troubleshooting solution. Would you spec the force of the rap in newtons or lbs per inch?

I'm thinking this technique is anecdotal rather than a tried and true troubleshooting technique. In desperation all options are on the table. I would be rather reluctant to use a bench P.S. to arch switch contacts. It seems to be such a brute force solution. Then again, I have banged on the side of a failed hard drive because hope springs eternal.

Sean

I was also taught to never file or use abrasive cleaners on switchgear contacts as that would damage the plating; doing so would also accelerate future damage. Instead to always use a proper switch cleaner, which I used to pull through on a piece of blotting paper if the dirt was stubborn.

John, that's certainly what we have found on The Bombe which uses plenty of relays.  Any dirt or corrosion is cleaned with a diamond file.  If any contact is arcing it tends to weld those contacts shut!  I think Kyle is talking about sacrificing a few to find out the current where that doesn't happen but I'm amazed it actually cleans the contact.  Interesting....