Tuesday, 22 May 2012

Frogs and powersupplys and Circuit Cellar

The £1 frog croaks as you get near to it - got to be something interesting in there!

Now all that Chelsea stuff is over I have just got back into the workshop. You can't beat the smell of flux and glue. On firing up the workshop's IT system, it collected all the e-mails it has missed for the last few days and among them was a note from Circuit Cellar magazine to let me know they have mentioned my workshop blog on their website. See, somebody must read it! You can see what they had to say HERE

Frog guts!
Meanwhile, on a trip to the local High Street on Saturday Sue managed to pick up one of the frogs mentioned by Dave at the bottom of HSBH 3, which you can read HERE. I have not had a chance to have a look at this thing so I was about to use some 'percussive maintenance' to open it when I discovered the works can be pulled out without damaging the frog. I am not sure what we have here but I will get onto it tomorrow. The small circuit board is just loosely stuck in place and there is what looks like a light censer in its mouth. Looks like this could have lots of uses and for just a pound it even comes complete with batteries!

Putting the frog to one side for now, I decided to take a closer look at an unused AXT computer switched power supply I have had laying around for a few years. These things make a good bench top power supply, if you can only get then to power up. After a bit of head scratching it occurred to me that there might be a bit of a clue in the name. When you connect your computer to the mains supply the power supply does not start until the start button on the front of the computer is pressed. After a bit of a Google search I found a pin-out diagram for all the plugs attached to the huge harness HERE. I should say at this point, unless you know exactly what your are doing, DON'T DO THIS AT HOME.

Don't play with this unless you really know what you are doing. Even when it is off there
is likely to be some stored power in those large capacitors

Pin 14 (of the 20 pin motherboard connector) usually has a green wire attached to it and the pin is marked: PS_ON which means Power Supply ON. If you connect this wire to a ground pin, of which there are several on the plug (Pins: 3,5,7,13,15,16 & 17 are all ground pins) the Power supply will run continuously. If you connect the green cable to ground via a switch, you will be able to turn the supply on and off. I intend to use this as the basis for a bench power supply. I will let you know how I get on in due course.


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