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Old 20th Nov 2021, 11:27 am   #1
Electronpusher0
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Default Haigh Wobbulator is there sufficient interest for a PCB?

Mods please move this if it is in the wrong section.

There seems to have been a resurgance of interest in the Haigh Wobbulator on the forum.
I posted my build of the wobbulator and a timebase on this thread

https://www.vintage-radio.net/forum/...d.php?t=172685

For a long time the coils were considered unobtainium but in that thread I describe some substitutes I have found, 3 out of the 4 have direct substitutes and the 4th can be made by removing the capacitor in a standard IF coil.

In the thread I also describe my improved timebase and a mod to overcome a shortcoming of the Haigh in that as you vary the sweep width the centre frequency moves, its the lower edge that remains fixed. My mod keeps the centre frequency fixed.

I have also been approached by another member about the pcb and the possibility of getting a design done.

So this post is to gauge the level of interest in a pcb for the combined Wobbulator and timebase pcb, designed on KiCad and made by JLCpcb.

I propose to sell a "kit" of the pcb and coils together, the coils cost about 12 for the 4 and the board would be about 2, I would add a couple of quid per kit to cover my time so probably say 16 plus postage. Price to be confirmed when the boards are ordered.

If you would be interested in the "kit" described please post a reply.
I would need at least to sell on at least 5 boards to make it worth while.

Peter
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Old 20th Nov 2021, 11:33 am   #2
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

Hi Peter, yes please, count me in. Jerry
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Old 20th Nov 2021, 12:11 pm   #3
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

Hi Peter,

+1 more.

Regards - Andrew
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Old 20th Nov 2021, 12:37 pm   #4
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

Yes please. And it won't have far to come
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Old 20th Nov 2021, 1:08 pm   #5
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

That sounds like an ideal winter project, could you add me to the list of takers please?

Cheers
Chris
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Old 20th Nov 2021, 2:32 pm   #6
David G4EBT
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

Just a little note of caution which I've mentioned in other threads to highlight a wiring error in the wiring of the range 3 & 4 coils. The circuit diagram in the article is correct, but the wiring diagram has an error. On the PCB overlay in the article, the range 3 & 4 coils need to be swapped over, as a glance at the circuit in comparison with the layout will show. When I built mine back in 2013, I didn't discover that error until I checked the coverage of the ranges on my frequency counter, and noted that the coverage for these two ranges were wrong.

I've attached a copy of the page which contains the circuit, and the page on which I've highlighted the wiring error.

The original article was in Radio Bygones in 2003, when I started to get the bits together, and it took me ten years to get around to building it. A further eight years has elapsed since then, and I'm still waiting to get round to using it.

As well as the original coils being scarce/unobtainable (albeit Peter has found a solution to that), I believe the KV1236 Varicap Diode became scarce too. There were two joined together, which could be separated by snapping them apart.

There was a follow up article for an RF probe, which I and a few others on the forum built.

Hope that might be of interest and help.
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Old 20th Nov 2021, 3:05 pm   #7
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

I would be interested in a board please.
Dave
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Old 20th Nov 2021, 3:27 pm   #8
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

I'd like a kit please.
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Old 21st Nov 2021, 7:40 am   #9
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Default Re: Haigh Wobbulator is there sufficient interest for a pcb?

In my thread linked in the first post I also found a substitute for the Varicap.

Looks like there is enough interest to layout a pcb, I'll get started.

Thanks David, the wiring error is noted.

Peter
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Old 21st Nov 2021, 9:06 am   #10
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Hi Peter, I would also be interested in a kit.
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Old 21st Nov 2021, 12:05 pm   #11
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Good news then Peter, sounds like you will be rather busy! BTW there are plenty of NOS varicaps offered on ebay, I have ordered a pair of KV1236s for under a fiver in anticipation.
Cheers
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Old 21st Nov 2021, 11:27 pm   #12
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Hi Peter.

Can you put my name down for one kit please.

Regards,
Symon
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Old 22nd Nov 2021, 2:49 pm   #13
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

I would be interested in a kit please Peter.
Thanks
Mike
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Old 23rd Nov 2021, 9:15 am   #14
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

I have started the pcb process but I would appreciate some opinions regarding ground planes.

The original pcb for the Haigh wobbulator is single sided (see attached).
When I lay out pcbs I like to place a ground plane on the top side, as I did with the Minimod pcb. It is as cheap to get double sided pcbs made as single.

What do others think about the wisdom (or otherwise) of putting a ground plane on the wobbulator pcb, would the screening help or would the additional capacitance affect operation?

Peter
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Old 23rd Nov 2021, 12:12 pm   #15
Chrispy57
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Hi Peter,
I guess the issue is that you would be skipping the prototype stage and going straight into production for a number of "customers" on this project with an unknown risk and little potential benefit over a tried and tested, decades old design. Your obvious experience and expertise inspire confidence in the decision you make.

Cheers
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Old 23rd Nov 2021, 12:50 pm   #16
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Thank you Chris, you are right, I will try to mimic the original pcb for the wobbulator section of the board.

Peter
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Old 23rd Nov 2021, 3:49 pm   #17
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

The original artwork for the PCB didn't reproduce very well - not good enough to create a UV mask from, so I cleaned it up so I could etch my own. I appreciate that you'll be creating new artwork in Kicad Peter, and sending Gerber files to JLPCB, but for what it's worth, I've attached the tidied up layout from ETI/RBI articles that I used for my mask.

As Chris says in post #11, there are scores of listings on eBay for pairs of KV136 varicap diodes at under a fiver post free (only one is needed). So with the coils, varicap & PCB all sorted, there are no impediments. Great to see another useful item of homebrew test-gear from yesteryear. Probably the last published project from the once prolific enigmatic mystery man who went by the name of 'R.F. Haigh', who left no trace, other than a legacy of well designed projects - notably simple multiband receivers.

Well done in your sterling efforts to help keep home-brew alive Peter.
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Old 23rd Nov 2021, 5:40 pm   #18
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Hi Peter,

I'd like to put my name down for one of these kits too, please.

Quote:
Originally Posted by David G4EBT View Post
Well done in your sterling efforts to help keep home-brew alive Peter.
+1 to that,

Colin
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Old 24th Nov 2021, 3:13 pm   #19
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Attached is the schematic transfered to Kicad, it still needs a final check.
The transistors are not critical, anything that conforms to the Elektor TUP & TUN definition will do. The PNP ones need to be able to be bonded together thermally however.
Next step is assigning footprints. I already have a footprint I created for the coil on the minimod I can reuse.
Then its the actual pcb layout.

Peter
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Old 24th Nov 2021, 3:22 pm   #20
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Default Re: Haigh Wobbulator is there sufficient interest for a PCB?

Peter - I already have most of the components for this, but not the PCB. Could you put me down for a PCB when it's available, please?

Mike
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