Zel's Fleet Blog - BX, Jag XJ-S, Sinclair C5, Mercedes 208D & 230TE, AC Model 70.

[Zelandeth]

I guess being an older design explains the passing resemblance to prior valve designs then. Have to admit I've not worked on much transistorised kit from this era.

Just actually measured it, and yes I definitely need a better 60Hz source. We're gaining approximately 2.5s per minute at the moment so that's never going to work. I make that 62.1Hz if my math is correct.

Guess if it came down to it it wouldn't be the most complicated thing to build...all I need is a decently stable frequency source - getting the 110V bit isn't hard, sure I've got some old toroidal mains transformers from scrapped stereo equipment that could be repurposed into step up rather than step down roles. Only talking a max of about 13W here so power handling doesn't need to be huge. Just needs to actually be reasonably close to being 60Hz.

[CitroJim]

Guess if it came down to it it wouldn't be the most complicated thing to build...all I need is a decently stable frequency source - getting the 110V bit isn't hard, sure I've got some old toroidal mains transformers from scrapped stereo equipment that could be repurposed into step up rather than step down roles. Only talking a max of about 13W here so power handling doesn't need to be huge. Just needs to actually be reasonably close to being 60Hz.

I believe details of how to build a suitable low-power 60Hz source can be found on the Vintage Radio forum Zel... A search should find it. I know there's been discussion about running 60Hz devices in the section that deals with electric clocks and the like...

The plan you outline would indeed work well... No problem in reversing a small mains transformer to make it a step-up when dealing with such low powers...

[Zelandeth]

The design in my head has grown arms and legs somewhat...though it's been the best part of 20 years since I've actually tried to design a circuit to do something useful from scratch so I'm kind of enjoying that.

I did think about keeping it simple with a basic oscillator...though I could see trying to trim it to be precise enough to be a bit of a pig. It also removes one of the thing I like about clocks like this, and that's being phase locked to the mains - so inherently very accurate (on average!).

So can't we use a PIC? Sample the mains frequency in, the count the pulses and use that to trim the internal oscillator using some simple math to keep the output frequency 1.2 times the input...then use some quick and dirty D-A conversion on the output (we're basically just going rail to rail so it doesn't need to be pretty), maybe apply some filtering to minimise the horrible harmonics I'm sure would be in there, and stuff that into an amplifier feeding into an appropriate transformer.

Bingo...60Hz out, but still phase locked to the incoming mains with the inherent long term stability that comes with it.

Can I actually remember how to DO about 70% of that from the last class I had on the subject back in 2004? Uuuh...not so much!

I'd by lying if the idea of a thermionic frequency changer getting involved hadn't occurred to me... though that would be somewhat ridiculous, plus being designed to generally operate at RF frequencies trying to make something behave in a stable manner at this end of things would probably be a nightmare.

It's a shame that there's not a convenient multiple between the two frequencies (that I'm aware of), as just being able to multiply by X and then divide by Y would be far easier...

Or I could just build a simple crystal controlled oscillator and accept that it's probably going to be more than accurate enough for this application!

Might be a good excuse to buy myself a new scope too...the fact that you can pick up a Rigol DS1054Z for £3-400 new these days is just nuts when you look at the feature set, you could have only dreamt of on a scope 10X the price only 10 years or so ago.

[xantia_v6]

There are many ways to skin this particular cat.

If you have a transformer with a center tap on the low voltage end, you can have 2 single ended driver's, a bit simpler than a bridge.

If you want to get techie, you can pulse width modulate the driver's at a few 10s of kilohertz to cancel out the 60hz harmonics while not needing linear drivers.

At the simple end, you can make a PLL with a couple of CMOS ICs, filter it and feed it into a bridge amplifier chip from a car radio.

[mickthemaverick]

Seems a lot of brainwork and component gathering when you could just get one of these Zel!! :

https://www.ebay.co.uk/itm/144512830418 ... R5LS9pCJYQ

[Zelandeth]

Seems a lot of brainwork and component gathering when you could just get one of these Zel!! :

Well I do have an open invitation to re-home this once I figure out the logistics... it's only 550 miles away...



Sure it wouldn't be at all heavy and difficult to manhandle into the back of a van...

This evening our two fluffy idiots got a bath. The reaction to this is quite different from the pair of them.

1. "I'm wet. I don't like it. It's all your fault. Grump."



2. "Hey, I'm all wet! That was so much fun! Can we do it again?"



Much Derp.



Then went after the pair of them with the slicker brush and removed several cubic feet of fluff from them.

The house now smells very distinctly of wet dog. What fun.

[CitroJim]

Well I do have an open invitation to re-home this once I figure out the logistics... it's only 550 miles away...

That's one solution to the current energy crisis Zel... Run it on old chip fat for free electricity...

Job's a good 'un!

[Zelandeth]

It's MOT time for the Caddy tomorrow so I gave it a quick clean today. I always try to turn up with my cars in a reasonably presentable state.



Still doesn't scrub up bad for a 20 year old van.







Also took the wire wheel to the crusty looking bit on the sills, which looked like this after I'd blasted the loose crud off with the pressure washer.



Then after this was hit with the wire wheel.



Seems perfectly solid. I've just thrown some Vactan and (not quite the right shade) silver paint on it for now.



It's better than crusty rusty anyway. Then I went round and checked all the obvious stuff like lights, making sure the washers weren't about to run out of water, stuff like that.

Then we'll just have to wait and see...first time I've put this through a test so will be a little nerve wracking.

[CitroJim]

All the best with the MoT Zel

Do please feel free to pop round and say hello. It'll be great to see you

[Michel]

All the best with the MoT Zel

Do please feel free to pop round and say hello. It'll be great to see you

Maybe l shall join you both for a cup of tea!

[CitroJim]

All the best with the MoT Zel

Do please feel free to pop round and say hello. It'll be great to see you

Maybe l shall join you both for a cup of tea!

Please do Mike It'll be magical to see you You'll have to bring your own tea as I've not touched a drop since I had Covid at the start of lockdown. It changed my taste for all sorts of things... Coffee only here and no real milk either although I can offer a bit of lactose-free stuff

I'll be busy working on Bluebell for most of today...

[Michel]

All the best with the MoT Zel

Do please feel free to pop round and say hello. It'll be great to see you

Maybe l shall join you both for a cup of tea!

Please do Mike It'll be magical to see you You'll have to bring your own tea as I've not touched a drop since I had Covid at the start of lockdown. It changed my taste for all sorts of things... Coffee only here and no real milk either although I can offer a bit of lactose-free stuff

I'll be busy working on Bluebell for most of today...

Real or decaf coffee Jim? I'll be with you 1130-12 ish..

[CitroJim]

Real or decaf coffee Jim? I'll be with you 1130-12 ish..

All types Beans freshly ground, properly brewed, instant and both high caffeine or decaf! I do good coffee and good flapjacks and cake to go with it

See you soon!

[Michel]

Real or decaf coffee Jim? I'll be with you 1130-12 ish..

All types Beans freshly ground, properly brewed, instant and both high caffeine or decaf! I do good coffee and good flapjacks and cake to go with it

See you soon!

Maybe tomorrow Jim, I got called out!

[Zelandeth]

Given that my prep work, on a 20 year old van consisted entirely of checking lights etc and a really quick clean I'll take that!



Tester was complimentary of the overall condition I thought.

Blew 0.2 m-1 on the smoke test, a definite improvement on the 0.92 from last year. Always nice to see hard numbers to show improvements you've made.

The brake line will be absolutely fine with a bit of clean up and some rust protection applied. The factory coating is just flaking off a bit near the end.

So no drama which is always a relief.