UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - American 60Hz clock

julie_m · 12th Jul 2019, 8:58 am

There is no need to worry about the waveform, just as long as it is symmetrical (for the sake of the permanent-magnet armature). A crystal oscillator and suitable divider chain will do fine; the division should ensure symmetry. Use the Q and Q' outputs from your last flip-flop to drive the gates of a pair of MOSFETs, one drain to each end of the centre-tapped secondary winding of a suitable transformer, the tap to the unregulated supply and the primary to the clock motor.

Small transformers tend to have lousy regulation, so one rated for 18-0-18V from a 230V supply probably will give about the right output with a 12V DC supply. The clock should still run from a reduced voltage.

12th Jul 2019, 8:58 am	#8
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: American 60Hz clock - Will it run on pulsed DC? There is no need to worry about the waveform, just as long as it is symmetrical (for the sake of the permanent-magnet armature). A crystal oscillator and suitable divider chain will do fine; the division should ensure symmetry. Use the Q and Q' outputs from your last flip-flop to drive the gates of a pair of MOSFETs, one drain to each end of the centre-tapped secondary winding of a suitable transformer, the tap to the unregulated supply and the primary to the clock motor. Small transformers tend to have lousy regulation, so one rated for 18-0-18V from a 230V supply probably will give about the right output with a 12V DC supply. The clock should still run from a reduced voltage. __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.