audio-talk

For reference for anyone bothered, this is the dial gauge setup, it can be fitted to the mill or the lathe using a simple machined bracket. I'd just like to say "Thank you, Ant" for that idea. I bolted a nice rigid bit of vertical aluminium angle to the back of the saddle of my Bantam lat...

Thanks for that. I’ll have to measure it and see how far out it is. Do you know if it’s drift in the thermocouple, or some other mechanism? Funnily enough, I recently had to up the temperature by 20 degrees to get solder to melt a little faster. That's exactly the problem I had. I assume it's corro...

Nice work. One of your photographs shows a modern Weller temperature-controlled iron. They work beautifully when new, but as they age, tip temperature falls relative to what is claimed. The older Magnastat is much better. Old paxolin PCBs are very prone to tracks lifting and need a great deal of car...

OK, so it doesn't change with volume level, putting it after the volume control. And is the same in both channels, making it something common to both channels, which makes it power supply. But you've replaced the electrolytics, which would be the first suspects. I would suspect stuff around the main...

New battery fitted and irritating sounds switched off. I'm trying to think when I bought my DCA55. The ESR60 is more recent and was bought about twenty years ago. Both are very nice little instruments, but you can't lob them in a tool box - that's how they switch on and flatten their expensive batte...

I perennially found Peak instruments with flat batteries both at work and at home, hence the boxes. A moment ago, I was going to look in the menu to gag the beeper, but when I switched my DCA75 on, it chirped at me then said "low battery". :D Turning to your thyristor gate current requirem...

Don't be in too much of a hurry to get rid of the DCA55. My DCA75 Pro irritated me (beep) and has been relegated to the back of the drawer, with the DCA55 and ESR60 at the front. Peak testers fit nicely in small baby bud boxes, protecting them from being switched on and flattening their batteries.

Oh yes. A potential divider is always a potential divider. For AC heaters, you can help matters by adding a pair of 100R resistors from each end of the heater winding to chassis (even if the heater winding already has a centre tap). That will add some low frequency attenuation. Try simulating it in ...

It's not in the least critical. In series, they become the capacitor for the Quasimodo. In parallel, they become the lower leg of a capacitive attenuator for which the upper capacitor is the transformer's Cps. The larger the capacitors, the better the common-mode attenuation. However, larger capacit...

I've even started adding the two caps and resistor to PS PCBs now, to make it easy to implement Split the capacitor across the secondary in two and connect the centre to chassis and you have the common-mode attenuator mentioned earlier. Or, decide to fit those two capacitors and use a capacitor of ...

Oh, and I've just noticed from that photograph of PSU board that there appear to be capacitors across the diodes. I know we all used to do it, but it's a "bad thing". The intention was to damp switching transients as the diodes switched off. The reality is different. 90% of the time, all t...

I have "The Moog Strikes Bach". Like Wagner, not as awful as it sounds. Nice dishes.

MistyBlue wrote: ↑Sun Aug 25, 2024 5:04 pm This is what I had in mind, and the transformer I have currently for the valve driver stage.

If I were you, I'd short circuit the primary, short circuit the secondary, and measure capacitance between the two, with that copper foil earthed and without. Low Cps is important.

Any chance of a thread on this? We'll see. Yesterday I got over a nasty two-week bout of covid, yet today realise I've caught a cold. Projects tend to progress on geological time scales around here, being subverted by the latest wheeze. Still, a few significant parts have been made; platter sleeve ...

It's worth doing on anything, but especially for heaters. Toroids have very high CPS whereas split bobbin EI are much lower. If you put self-adhesive copper tape (as sold to gardeners) around the laminations that will effectively connect them to RF earth and slightly reduce CPS. Solder the 10n capac...