On 02/16/2012 01:41 PM, Ullrich von Bassewitz wrote: > > On Thu, Feb 16, 2012 at 12:34:07AM +0100, Rob Clarke wrote: > >> Q7) The CBM-II PSU's all supply a 50/60hz signal from the PSU, which >> I think is just used for the TOD clock on the CIA. As I'm unlikely >> to find this on a modern PSU, is there a really simple way of >> generating this signal? > > Optocoupler has already been named. In the old days there have also been > people who fed the signal by an 555 oscillator. Another possibility would be the ELM440 (60Hz) or ELM446 (50Hz). They are 8pin ICs that use a 3.58MHz crystal and supply the 60 or 50 Hz plus a 1 Hz signal. Datasheet can be found here: http://elmelectronics.com/ebench.html Or you build this: ___ R2 +---|___|--- +5V ___ R1 | ------ -----------|___|-------*-----+ *------+ |/|||/| | ...|.......|.. | |/|||/| --- . --- |/ . | |/|||/| TR1 D1 \ / . / \ => | . O1 | |/|||/| --- . --- |\ . | |/|||/| | ...|.... V . | ------ -----------------------*-----+ ....|.. | | | --- | GND | | +------------------------------------------+ | | |\ |\ +---| )O---*---| )O------- TICK |/ | |/ | ----- C1 ----- | --- GND TR1 = Transformer 230V => 6V 50mA (smallest you can get) D1 = 1N4148 R1 = 820 Ohm R2 = 1.8 KOhm C1 = 10 nF O1 = 4N35 I once built this to replace the busted PSU for an Amiga 2000 with a standard PC PSU for a friend. Even though the capacitor is not recommended to be hooked up like that, it worked for years without problems and produced a reliable 50 Hz signal without glitches. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2012-02-16 17:00:36
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