Search found 107 matches

by Morgan Jones
Tue May 21, 2024 4:46 pm
Forum: Jokes
Topic: A little light humour
Replies: 2729
Views: 1242879

Re: A little light humour

Bottom left looks like a pedicure set? Nut picks? No, no. Didn't you see a set like that in a Bond film where Bond was threatened by a villain with a set like that after Bond had offed the villain's mentor? It's a villain's torture set. It was in the film where Bond blew a lot of things up and race...
by Morgan Jones
Mon May 20, 2024 7:54 pm
Forum: Everyones Projects
Topic: Pye Sunrise Radio
Replies: 14
Views: 571

Re: Pye Sunrise Radio

Of course, at the time, negative feedback wasn't used so the amplifiers were pretty poor Interesting...😄 Ah, looks like I've wiggled a stick in a hornets' nest. What I should have mentioned is that the loudspeaker amplifier was invariably a pentode and for a portable set, run close to full power, s...
by Morgan Jones
Mon May 20, 2024 7:47 pm
Forum: General Vinyl
Topic: 60Hz oscillator for turntables (also produces three phase)
Replies: 17
Views: 721

Re: 60Hz oscillator for turntables (also produces three phase)

Actually, it's better to keep the three phase motor and use either a static converter or a rotary converter. For best finish, you need smooth rotation, and single-phase motors produce far more vibration than three phase. I chose a static converter over the (cheaper) VFD solution not just because I d...
by Morgan Jones
Mon May 20, 2024 10:15 am
Forum: General Vinyl
Topic: 60Hz oscillator for turntables (also produces three phase)
Replies: 17
Views: 721

Re: 60Hz oscillator for turntables (also produces three phase)

I bought a very informative book "Electric Motors" from ARCEuro (£7.75, I think). I thought like you that a rotary converter was essentially a motor/generator set, but apparently it isn't and the motor can be smaller than the load motor or motors. Sounds like it would be worthwhile for you...
by Morgan Jones
Sun May 19, 2024 11:08 pm
Forum: Everyones Projects
Topic: Pye Sunrise Radio
Replies: 14
Views: 571

Re: Pye Sunrise Radio

I bought a copy of "Radio! Radio!" last Sunday and it has pictures of Pye radios, so I'll look it up and let you know if I find anything. But radio started with music and entertainment - it wasn't all shipping weather forecasts! Obviously, anything you put inside must be valve (to get the ...
by Morgan Jones
Sun May 19, 2024 4:26 pm
Forum: General Vinyl
Topic: 60Hz oscillator for turntables (also produces three phase)
Replies: 17
Views: 721

Re: 60Hz oscillator for turntables (also produces three phase)

I forgot to include the phase tweak...
by Morgan Jones
Sun May 19, 2024 11:20 am
Forum: General Vinyl
Topic: 60Hz oscillator for turntables (also produces three phase)
Replies: 17
Views: 721

Re: 60Hz oscillator for turntables (also produces three phase)

A lathe or a mill requires a lot of power. Even a Class B power amplifier is only 78% efficient (maximum) from its HT power. And the idea of three push-pull 833 amplifiers to power a machine tool is mindboggling, but would give serious bragging rights. I looked up Harrison L6. Nice. I use a Transwav...
by Morgan Jones
Sat May 18, 2024 7:24 pm
Forum: General Vinyl
Topic: 60Hz oscillator for turntables (also produces three phase)
Replies: 17
Views: 721

60Hz oscillator for turntables (also produces three phase)

For my one hundredth post, I thought this might be useful. Running from a +/-15V supply, the state variable oscillator produces 60Hz sine and cosine waveforms of about 24V peak to peak, with amplitude set by VR1. This large amplitude means that the noise of the (TLO74) op-amp is negligible. If you n...
by Morgan Jones
Sat May 18, 2024 10:01 am
Forum: Valves
Topic: Dying Rectifier?
Replies: 28
Views: 1177

Re: Dying Rectifier?

Current valve prices are ridiculous. It's got so that I can no longer afford NOS valves, so it's just as well I have a decent stock. As mentioned, damper diodes (US) or efficiency diodes (UK) are an option. I use 6CL3 and 12CL3 (no top caps, but you need the right base and it isn't Magnoval). They c...
by Morgan Jones
Fri May 17, 2024 11:21 pm
Forum: Everyones Projects
Topic: Oracle Delphi mk1 Quick Restoration
Replies: 99
Views: 44294

Re: Oracle Delphi mk1 Quick Restoration

Wow; a choice of rotary tables! Yes, if you use a hex head nut, You will have plenty of meat in your carrier for head. And a skim off the head to remove the proud lettering will help. Is it really essential to remachine the stub? I suppose you know for certain, but I can understand your hesitancy. I...
by Morgan Jones
Fri May 17, 2024 7:36 pm
Forum: Everyones Projects
Topic: Oracle Delphi mk1 Quick Restoration
Replies: 99
Views: 44294

Re: Oracle Delphi mk1 Quick Restoration

I was making some swarf and just had a little thought about your cartridge carrier. There is room (just) to put an arced slot in the carrier behind the cartridge screws. That slot could be rebated underneath to take either the hex head of a screw or a nut. Ideally, you'd do a job like that on a turn...
by Morgan Jones
Fri May 17, 2024 4:41 pm
Forum: Valves
Topic: Dying Rectifier?
Replies: 28
Views: 1177

Re: Dying Rectifier?

Looks like the GZ33 was the guilty party. I've just looked up GZ37 prices. Blimus! And I looked up the GZ33 data sheet. Mea culpa. Yes, a GZ37 is actually less hungry in heater current than a GZ37.
by Morgan Jones
Fri May 17, 2024 12:31 pm
Forum: Valves
Topic: Dying Rectifier?
Replies: 28
Views: 1177

Re: Dying Rectifier?

Thank goodness for that!
by Morgan Jones
Fri May 17, 2024 9:25 am
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 173
Views: 17602

Re: TG "The Loudspeaker" Build (Sort of)

They'll soon be ready for the jolt of lightning to bring them into life. :D
by Morgan Jones
Fri May 17, 2024 9:21 am
Forum: Valves
Topic: Dying Rectifier?
Replies: 28
Views: 1177

Re: Dying Rectifier?

Try the GZ37. But not for very long as they draw a lot more heater current and your transformer might not be up to it. But I'd suspect a dodgy joint at the transformer. You'd be amazed how much pressure you have to apply to get a meter probe to make a contact, and that could be enough to disturb a n...