Search found 103 matches

by Morgan Jones
Sun May 19, 2024 11:08 pm
Forum: Everyones Projects
Topic: Pye Sunrise Radio
Replies: 5
Views: 42

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: 6
Views: 118

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: 6
Views: 118

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: 6
Views: 118

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: 26
Views: 648

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: 43885

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: 43885

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: 26
Views: 648

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: 26
Views: 648

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: 168
Views: 16752

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: 26
Views: 648

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...
by Morgan Jones
Thu May 16, 2024 7:10 pm
Forum: Valves
Topic: Dying Rectifier?
Replies: 26
Views: 648

Re: Dying Rectifier?

Can't say I've ever heard of anything like that before. Are you certain the 5V is always present at the rectifier? When the sound dies, are the heaters still lit? A GZ33 draws quite a bit of heater current and a dry joint in the heater wiring is always a possibility. A dry joint inside the valve's h...
by Morgan Jones
Wed May 15, 2024 1:43 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16752

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

I only have an ancient photocopy of the Tappan paper, but it really can be summarised by the "position braces to minimise the size of inscribed circles" idea.

Your summary of my box thoughts is correct, although I had to reread my article to realise that CLD = constrained layer damping.
by Morgan Jones
Tue May 14, 2024 11:32 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16752

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

I've been lucky; fully recovered. But I aim to avoid a third event.

They do, and obey the law of variable gravity that should be taught in schools; mass is proportional to distance carried and age of carrier.
by Morgan Jones
Tue May 14, 2024 6:01 pm
Forum: Speakers
Topic: TG "The Loudspeaker" Build (Sort of)
Replies: 168
Views: 16752

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

Ah, I should have added a smiley face or summat. Since breaking my back (for the second time) I have vowed to make lighter electronics. But it always seems to be heavy. :?