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Old 20th Nov 2021, 12:27 pm   #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, 12:33 pm   #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, 1:11 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, 1:37 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, 2:08 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, 3:32 pm   #6
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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, 4:05 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, 4:27 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, 8:40 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, 10:06 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, 1:05 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
Chris
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Old 22nd Nov 2021, 12:27 am   #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, 3:49 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, 10:15 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, 1:12 pm   #15
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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
Chris
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Old 23rd Nov 2021, 1:50 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, 4:49 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, 6:40 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, 4:13 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, 4:22 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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