19-04-2012, 05:24 PM
What an excellent post Colin, which goes a long way to demystifying transformers. (I wonder how many DAC90A OPTs have been chucked away when they could have been re-wound?)
I notice on the youtube video of the simple 'wave wound' hand coil winder based on the 'Gingery' design for a 'universal coil winding machine' that he used a calculator as a turns counter, which is a good idea. The orignal design uses a hand 'tally counter' - one of those little push button counters that tour guides and the like use to count people getting onto a tour coach so no-one is left behind. (They're quite cheap - about a fiver.) I've almost finished building that design as shown in the video below, but I found that the spring on the counter is too strong and caused the drive on the winder to slip. I therefore dismantled the counter and removed some turns from the spring to make it weaker. However, when I eventually get round to finishing the winder I'll remove the tally counter and firt a small pocket calculator, a small magnet and a reed switch. I'll then couple the switch to the = key on the calculator so that with each rotation of the winder, the magnet will close the reed switch and short out the = key just as would a press of the key. To start counting you press 1, then the + key twice to make 1 a constant ('k' in the display). After that, each time the = key is shorted by the reed switch it increments by 1 until you stop the coil winder, at which point the total number of turns is displayed on the calculator. Neat idea, and cheap too, with pocket calculators from Poundland!
Of course, in the video he seems to be using litz wire, or cotton covered, which poses anotehr challenge - like where from at an affordable price rather than a King's ransom!
http://www.youtube.com/watch?v=FIOocMoRsYQ
I notice on the youtube video of the simple 'wave wound' hand coil winder based on the 'Gingery' design for a 'universal coil winding machine' that he used a calculator as a turns counter, which is a good idea. The orignal design uses a hand 'tally counter' - one of those little push button counters that tour guides and the like use to count people getting onto a tour coach so no-one is left behind. (They're quite cheap - about a fiver.) I've almost finished building that design as shown in the video below, but I found that the spring on the counter is too strong and caused the drive on the winder to slip. I therefore dismantled the counter and removed some turns from the spring to make it weaker. However, when I eventually get round to finishing the winder I'll remove the tally counter and firt a small pocket calculator, a small magnet and a reed switch. I'll then couple the switch to the = key on the calculator so that with each rotation of the winder, the magnet will close the reed switch and short out the = key just as would a press of the key. To start counting you press 1, then the + key twice to make 1 a constant ('k' in the display). After that, each time the = key is shorted by the reed switch it increments by 1 until you stop the coil winder, at which point the total number of turns is displayed on the calculator. Neat idea, and cheap too, with pocket calculators from Poundland!
Of course, in the video he seems to be using litz wire, or cotton covered, which poses anotehr challenge - like where from at an affordable price rather than a King's ransom!
http://www.youtube.com/watch?v=FIOocMoRsYQ
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'
