Bits and Bobs

Had a day out with Bob M1BBV at Grantham rally today. Somewhat disappointed, it was much smaller than expected, and its a long way. But any trip out with Bob is always an experience! Intended to also take a walk out to the targets at Donna Nook, but the weather was awful.

After much deliberation, advice seeking and calculations, the resistors are on their way to create a grounding and static bleed unit in order to be able to safely fly a kite antenna. Annoyingly, there was a small winch at the rally that I could have got that would have made flying an antenna kite much easier!

One positive is that my gas bill is coming down. Seems the mild winter so far has reduced the wholesale price, and my supplier is quite good at tracking this and reducing prices. They are also still doing their £50 credit offer when switching using a customers personal link, so, i'll put that link at the bottom of this post!

I am now in a position to test some of the PRC344 scan controllers code features against the actual radio. This will be done by a mock-up with test clip wires, and will hopefully prove that the three key control inputs - synth lock, mute and over-ride, work as expected. One aspect of the controller that I hadn't appreciated, and that required some rather complex redesign, was the way the selector switches would behave if isolated!

Essentially, my plan was to use Schottky diodes to isolate my control lines from those of the switches, allowing the existing pull-up resistors to hold unused lines high, and to prevent the switches influencing the synthesiser by disconnecting the switches ground. Sounds like a sensible plan, until you remember that these are BCD switches! If I leave the commons of the switches floating - the net result is that any closed switch is pulled high by leakage through from the pull-ups! As best I can work out, this would completely screw up the system! So, ive designed an isolator module based on 4066 ICs to completely disconnect the switches!

I do still need to test this theory, before I build the isolator. If there is any way to do this without the additional electronics it would of course be preferable!


If anyone is interested in switching energy supplier, do your research, and if Bulb turn out to be good for you, then feel free to use my link to switch, and grab £50 credit! -
bulb.co.uk/