Project Delays

Its been some time since I posted on here, mostly due to being worked like a dog on overtime, but also some big household projects needed working on, and also training yet again for a charity walk.

Ive revisited the PRC344 battery warning project today. I'd forgotten about the modification needed to the v.1 PCBs! This is because I was let down by a supplier and am still waiting for the 100k and above resistors.

Needing to get at least some of these v.1 boards completed and up running, I tested the circuit on breadboard again tonight using 10k range resistors instead, just to prove that it works that way, which it does. I also tested various combinations of Ra and Rb in the 1-10k range and found a couple of combinations that give a 20.2v cut-off (4k7 and 6k8) or 18.7v cut-off (3k9 and 6k8). I'll have to check the minimum terminal voltages of the batteries and decide which to fit. I think though that 1v/cell really is best as a maximum discharge, so the 20.2v values will probably be chosen.

This will allow me to get at least a few of the boards working, at least until I run out of 0603 10k resistors! But I should at least be able to demonstrate one! Then, when the rest of the resistors arrive, the remaining boards can be made up with either 10k or 100k series.

Its now however almost certain that I will redesign for a v.2 board using 0805 size parts, this will allow the use of a better voltage rated and higher value capacitor for the timing, but I will also add the duty cycle control diodes as well.


Ive also, since last posting, acquired a WW2 rescue box kite (as used with the famous 'Gibson Girl' lifeboat transmitter) which I have repaired and restored. I am now in the process of building an antenna connection and protection unit, which will drain wind static and protect against electrical discharge. Once that is done, it will be time to attach an antenna wire, fly the kite and load up the Clansman!