04-08-2013, 05:52 PM
Thanks for reading my post Ted, and for your comments.
Yes, to use a calculator as a turns counter, you just fit a switch across the = contacts, then to start counting, you press '1' then the + button to make '1' a constant, then each time the = button is shorted, it increments by one. You can try it on a calculator of course. 1 + + then with each press of the = button, it counts upwards. I've already added this to my hand wave wound coil winder (yet to be use in anger!), but of course it's impossible to wind a field coil of many thousands of turns by hand. With fine wire obviously the speed won't be very great or it risks breaking the wire, but rather than use a reed relay and magnet, I think a micro-switch and cam will reduce the chance of contact bounce. Time will tell! (The other option would be a mechanical one, using a 'tally counter' operated by a cam. Cheap enough and originally used on the 'Morris Gingery' hand wider.
As I said earlier, it's not so much the number of turns that's relevant, but the weight of wire, which correlates to the resistance for each gauge of wire. I won't know until I've removed the field coil what gauge of wire was used. At this stage, I'm concentrating on re-building the power supply which is on a separate chassis from the rest of the radio. All stripped down ready to de-rust and re-spray the chassis and rebuild it. (It's the first time I've tacked a valved radio that's older then me!).
Incidentally, back in 2007 Gary Tempest wrote an article in the BVWS Bulletin which you can download off internet. Google: "Making a Coil Winder (mostly from the junk box)" The article has a lot of useful info about winding field coils. (Gary designed and built a CMOS IC turns counter using an interrupted light beam).
(Back bedroom is now full of stuff to go to Hornsea Rally Ted - all neatly labelled and priced up! Have you booked your table?).
Yes, to use a calculator as a turns counter, you just fit a switch across the = contacts, then to start counting, you press '1' then the + button to make '1' a constant, then each time the = button is shorted, it increments by one. You can try it on a calculator of course. 1 + + then with each press of the = button, it counts upwards. I've already added this to my hand wave wound coil winder (yet to be use in anger!), but of course it's impossible to wind a field coil of many thousands of turns by hand. With fine wire obviously the speed won't be very great or it risks breaking the wire, but rather than use a reed relay and magnet, I think a micro-switch and cam will reduce the chance of contact bounce. Time will tell! (The other option would be a mechanical one, using a 'tally counter' operated by a cam. Cheap enough and originally used on the 'Morris Gingery' hand wider.
As I said earlier, it's not so much the number of turns that's relevant, but the weight of wire, which correlates to the resistance for each gauge of wire. I won't know until I've removed the field coil what gauge of wire was used. At this stage, I'm concentrating on re-building the power supply which is on a separate chassis from the rest of the radio. All stripped down ready to de-rust and re-spray the chassis and rebuild it. (It's the first time I've tacked a valved radio that's older then me!).
Incidentally, back in 2007 Gary Tempest wrote an article in the BVWS Bulletin which you can download off internet. Google: "Making a Coil Winder (mostly from the junk box)" The article has a lot of useful info about winding field coils. (Gary designed and built a CMOS IC turns counter using an interrupted light beam).
(Back bedroom is now full of stuff to go to Hornsea Rally Ted - all neatly labelled and priced up! Have you booked your table?).
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
