"Electronic Organ" ('Stylophone') Magazine? Project ID / Info wanted

[ortek_service]

(Hopefully I've found the most-appropriate area for this request, as it's not quite completely Homebrew?)

I recently acquired an (Actually a two-octave 'Stylophone') "Electronic Organ" labelled blank PCB, from a Rally 'Junk Box' (Along with another 'S-DeC' "breadboard", so looking like from the 1970's) - See attached photo.

But it's not got any other of the usual Electronics magazine logo / reference numbers on it - Although it does very-much look like that kind of thing.
The PCB has been fairly professionally produced, with very flat Tin-plating (with the odd lumps at edge from roller-tinned?), but oddly is all undrilled.

And it's on some quite-vintage SRBP / Paxolin ? type material (rather than more usual FR4 etc Fibreglass that ready-made Electronics magazines project boards usually were on), that has rather-warped a bit.

It does look like there would be a conventional chain of resistors, tapped for each note, connected to a transistor-based oscillator (as no IC footprints).


So I was wondering if anyone recognises where this originated from?
- I've tried Google inc. a reverse-image search and looking at some old Electronics magazines from back then that did come up from search. But no luck so far finding this particular one.

TIA,
Owen

[Valvepower]

Hello,

Somewhere at the back of my mind when I was doing the Clavioline article for the Bulletin, I remember a 'stylus' organ project by (I think) F C Judd in Practical Wireless/Electronics, but it have even been Studio Sound.

F C Judd was a prolific author of organ/synth projects.

Terry

[ortek_service]

Thanks for the Info, which may be a useful starting point for further searches.

I do recall the F.C. Judd name - but more from PW articles on antennas and I hadn't know of his involvement with Electronic Music projects, as detailed a bit here: https://en.wikipedia.org/wiki/Fred_Judd

I did have a feeling this may be a Practical Electronics (Or maybe Radio Constructor) project. I think it looks maybe a bit too early for HE / EE, but possibly early ETI.

So I will have to plough through some old ones of those / their Indexes. Although I have seen some websites that have indexed many of the Music related projects from these, like: https://sdiy.info/wiki/Practical_Electronics_SDIY_articles_index

[kellys_eye]

The ETI organ was a 'touch' keyboard - not the same as the OP image. Just to save anyone looking for it!

[davidw]

I've found it, PW December'72 by D. Smith. The board was available via the PW pcb service.
https://www.worldradiohistory.com/UK/Practical-Wireless/70s/PW-1972-12.pdf

[SiriusHardware]

Good find, Dave. I think I might be tempted to fit precision presets in the resistor ladder positions because I think the 'up to 10Hz out' factor might upset those of a sensitive musical disposition. That wouldn't be me, but a fellow radio amateur who also happened to be a music teacher instantly noticed that my microprocessor-derived '1750Hz' toneburst was 'flat'. It was 2Hz out, (1748Hz).

Even with the ability to 'tune' each note individually from highest to lowest in succession, it will be liable to drift like mad.

[David G4EBT]

That brought back memories!

I made that for my young sons, then aged 4 & 8 - now aged 56 & 60.

They had endless fun with it.

I etched my own PCB. Why, you may think - when it was only 80 pence to buy, including P&P?

But 80p in 1972 equated to £14.80 in 2024.

https://iamkate.com/data/uk-inflation/

[ortek_service]

Although I've noticed they didn't include the text for each note, on the PCB-artwork they did at least show at the start of the article - that is on my ready-made one / the photo's of completed unit (Which also has rounded corners, that mine doesn't).

The PW cover price of that issue was 20p and is now £5.99! (Although rather-cheaper via subscription, especially multi-year, I've now got). So that could make it now around 30x, so £24! but I guess Electronics magazines have gone-up more than inflation (especially with a lot less sold these days).
- It was said that prices doubled every 10years and at just over 50yrs ago, then that would be >32x. But inflation had probably been rather lower than the 70's until the last few years.

[ortek_service]

Originally Posted by davidw

I've found it, PW December'72 by D. Smith. The board was available via the PW pcb service.
https://www.worldradiohistory.com/UK/Practical-Wireless/70s/PW-1972-12.pdf

Originally Posted by SiriusHardware

Good find, Dave. I think I might be tempted to fit precision presets in the resistor ladder positions because I think the 'up to 10Hz out' factor might upset those of a sensitive musical disposition. That wouldn't be me, but a fellow radio amateur who also happened to be a music teacher instantly noticed that my microprocessor-derived '1750Hz' toneburst was 'flat'. It was 2Hz out, (1748Hz).

Even with the ability to 'tune' each note individually from highest to lowest in succession, it will be liable to drift like mad.

davidw: Yes, thanks very-much for finding this. I do actually have that original paper-issue in my collection(s) of these, so I'll have to dig it out (as well as reprint the relevant bits from the pdf-scanned copy online).

At first glance of the cover-photo, it looked more like a tobacco-tin case had been used, and I wouldn't have guessed they'd actually build it into a lunch-box! (Especially as they've rounded the PCB corners-off, when it seems the PCB-facility that made the ready-made ones didn't have a computer-controller PCB-router to so this automatically back then).
And the 'D.Smith' Author wasn't a familiar one to me (Although I didn't start getting these magazines originally until the end of the 70's).


Graham: I think (re)tuning this would be rather difficult if all the presets were in-series - You'd have to do it all in an sequential-order from the right end. Although maybe get away with just adjusting 'master' one at end of chain to compensate for temperature / battery voltage etc. variations, rather than adjusting the whole lot.
But knowing the rather (odd-harmonics square-wave oscillator ?) harsh sound that Stylophones typically sounded like, with few people able to get a good tune from them, then I'm not sure a few Hz off would be the main problem!

That many presets - especially multi-turn ones could make it rather expensive to make. Never mind the obsolete Germanium transistors, that are now quite expensive. But I think I've got most of these transistors / equivalents, so once I find these (and my PCB drill), I'll probably have a go at assembling it all online - I can't see this PCB being that valuable left unbuilt.
Although it would be good to find a way of flattening the warped board first (In the absence of having a heated PCB press, used to laminate-together the individual doubled-sided cores of multilayer FR4 etc boards).

If anyone is inspired to make one, then maybe this more-modern detailed design may be easier: https://www.instructables.com/A-Stylophone/
I do seem to recall back in the 70's my Brother building one - from the 'Adventures with Electronics' Tom Duncan book? But may have only built the oscillator / AF amp, and not the resistors / keys chain (Although maybe done with screws on wood, like some other projects and never managed to buy an S-DeC back then).

[Valvepower]

Hello,

This is possibly the F.C. Judd Organ I was thinking about in PW.
https://www.worldradiohistory.com/UK/Practical-Wireless/70s/PW-1971-11.pdf

Anything more would need a separate thread as this would be heading off topic and out of the scope of the section.

Terry

[ortek_service]

Thanks - a quite similar design, but more involved so that was only part 1.

Where they did use pre-sets adjustments for each note (with a master pitch adjustment), as Graham suggested may be better.
As well as a proper DIY mechanical keyboard.

So all something to bear in mind when making the 'later smaller lower-cost' version by D.Smith, that my PCB was originally for.

[SiriusHardware]

It's certainly true that making all the resistors in the original design adjustable would require them all to be tuned in strict order from highest note first to lowest, and then any disturbance to the adjustment of one of the higher notes would also affect the tuning of all notes lower than the one being adjusted.

Not really in the spirit of the thing... I might be tempted to utilise the printed circuit 'keyboard' and resistor chain and the original audio amplifier circuit, but replace the oscillator with a small Arduino - use an Arduino analogue input to read the keyboard resistor chain and, based on the reading from that, generate precise microprocessor generated note frequencies using a lookup table of from-to input voltages against timing values for each desired note frequency.

[davidw]

Originally Posted by SiriusHardware

Good find, Dave.

Happy to help.
It helped that I have a number of PW compilations on disc thanks to MrsW buying me christmas presents! So armed with the publication date just adding the link was easy!

[Simondm]

The resistors in the original Stylophones were non-standard values, and as such were relatively expensive.

The Stylophone circuit was redesigned around 1971, to eliminate discrete resistors for the note values, and to simplify (four transistors were eliminated, as those originally had to be selected at the factory).

SIL resistor sets (ceramic?) were introduced, specifically for the purpose. In the small Stylophone designs, there are two of them, each covering ten notes. This also meant that component placement mistakes were fewer, as the boards were populated by home workers on piecework, but went back to the factory for flow soldering.