Alternator Motor Update

So my last post about an alternator to brushless motor conversion seemed to draw some interest, but people were asking some details so I drew up a quick diagram in inkscape last night.

Using a car alternator as a ‘brushless’ motor

So I’ve been tinkering with the idea of using a car alternator as a motor, and got it to work yesterday. Here is the result:

Revive ‘dead’ sealed lead acid UPS batteries

Just to begin, this guide is not a fix-all solution to dead uninterruptable power supply (UPS) batteries, I will describe what the cause of one particular, common failure mode for sealed lead acid batteries is, and the solution.

Project Updates

So I’ve been busy over the last few days on a few projects.

First, a quick and simple wood frame for 3x 1W solar panels I purchased for $9 a piece. I plan to add a shunt controller, or at the very least a simple LM317 regulator set for 13.7-13.8V, because the solar panels are happy putting out a unloaded 23V!.

Yet another quick and dirty project, during my post-exam cleanup I decided I wanted to build a stand for my printer to sit on so that I can store stuff (ie: paper) underneeth it. Just old spare MDF from Ikea furniture. Always a good hack for anyone with flat pack furniture that they can’t be bothered to sell.

Another project that is unfortunately a bit of a failure is a big rackmount power supply I built. Using a beefy transformer it supplies 13.8VDC regulated, at high current (20-40A). Unfortunately the transformer I used was a microwave oven transformer, re-wound for low voltage. The transformer contains a shunt, and the laminations are welded together, shorting them and creating a ton of wasted power, and high idle current. Testing with a proper meter, I found out that the idle current is 6A, with a power factor of 0.12! Once I replace the transformer, the power supply should be rock solid and reliable.

Enough of that rant, the technical details:
The power supply uses 42000uF in the smoothing filter, 2x ISOTOP/SOT-227 dual diode modules for rectification, and 4x 2n3055 pass transistors with a LM723 regulator. The inside is a bit of a rats nest, however it works well and even *with* the voltage sag due to the transformer being very lossy, I can push at least 20A within a range of 12-14V. Note that using fuses is a very good idea with a power supply that has a very large short current, and the fuse block is mounted behind the front panel (those 2 screws on the right).

Future additions include: more binding posts, and a volt/current meter setup, along with the replacement transformer.

Last but not least, new gear! I’m studying for my amateurs license, and I’ve already picked up my radio, and a cheap (as in free) tuner.

Hack – DIY Cheap Vacuum Pump/Vacuum Tweezers

I started this hack after salvaging a gigantic ghetto token ring hub using a heat gun, and having dozens (read near a hundred) SMD IC’s which needed to be sorted, and my tweezers were simply not up to it. Knowing that real vacuum tweezers can cost more than the budget of hobbyists, I thought of a nifty way to make vacuum tweezers on the cheap.