Search found 1298 matches

by Pr0f
Sat Feb 17, 2024 11:13 am
Forum: General QL Chat
Topic: My rare old QL version AH
Replies: 22
Views: 1066

Re: My rare old QL version AH

No photo's I'm afraid - but if you look at the issue 5 board - there is a wire link or zero ohm resistor that connects pin 40 to VCC - it's marked on the PCB as a diode - and that's the first clue - this is the VCC for battery - which should be a wired or'd pair of diodes - one that from VCC to pin ...
by Pr0f
Fri Feb 16, 2024 7:32 am
Forum: General QL Chat
Topic: My rare old QL version AH
Replies: 22
Views: 1066

Re: My rare old QL version AH

The battery area was under the heatsink and near the modulator - but I've never seen a board fitted with it. I did make this mod myself on and old QL, but it involves some tweaking with the reset signal during power up - if I did it again I'd use one of the power management chips that locks out the ...
by Pr0f
Thu Feb 15, 2024 3:22 pm
Forum: Hardware
Topic: QL PSU Voltages
Replies: 20
Views: 706

Re: QL PSU Voltages

That should be more than enough I would have thought
by Pr0f
Thu Feb 15, 2024 1:58 pm
Forum: Hardware
Topic: QL PSU Voltages
Replies: 20
Views: 706

Re: QL PSU Voltages

One thing I would say - Charlies vRetro uses some sort of stepped square wave format for the AC voltage - it works fine with the power circuity in the QL for generating +/- 12V using the small L series TO92 regulators (look like transistors), and I don't think this AC voltage is used any where else ...
by Pr0f
Thu Feb 15, 2024 1:54 pm
Forum: Hardware
Topic: QL PSU Voltages
Replies: 20
Views: 706

Re: QL PSU Voltages

I know that if I have too much plugged in (curse those backplanes :-) ) the vRetro will gracefully abort trying to power the QL up. but it will happily run one expansion card in the QL no problem. I can't remember what spec my little power supply is, but I think it's 12V at 2.5A - which provides mor...
by Pr0f
Thu Feb 15, 2024 1:20 pm
Forum: Hardware
Topic: QL PSU Voltages
Replies: 20
Views: 706

Re: QL PSU Voltages

What's the symptoms with the vRetro psu?
by Pr0f
Thu Feb 15, 2024 11:48 am
Forum: Hardware
Topic: QL PSU Voltages
Replies: 20
Views: 706

Re: QL PSU Voltages

But the input to the 5V regulator should be about 9V DC I always thought (and have measured - when the QL is on). The regulator will work if the voltage is about 1-1.5V above the output voltage of 5V.
by Pr0f
Thu Feb 15, 2024 11:46 am
Forum: Hardware
Topic: QL PSU Voltages
Replies: 20
Views: 706

Re: QL PSU Voltages

Yes - if using a multimeter - put the black lead on ground - a good place that's convenient is the modulator housing, and then use the red probe to take your readings - but if the voltage you are measuring is AC - then you will need to switch the multimeter to AC range for that reading. You will get...
by Pr0f
Wed Feb 14, 2024 4:16 pm
Forum: The Off-Topic Section
Topic: Neo6502
Replies: 6
Views: 892

Re: Neo6502

ditto - and I like the Olimex version and the metal case you can get for it too.
by Pr0f
Tue Feb 13, 2024 8:39 am
Forum: The Off-Topic Section
Topic: Today I Received...
Replies: 642
Views: 285894

Re: Today I Received...

I keep seeing those advertised - I've got a couple of the lilygo boards already - and they are wonderful little things - but I am struggling to justify why I might need this one ;-)