Strobotron

[Grahame Marsh]

http://www.sgitheach.org.uk/strobotron.html

Enjoy
Grahame

[John Rehwinkel]

> http://www.sgitheach.org.uk/strobotron.html

Nice job! I have one of the commercial units using that neon strobe tube. And I understand your comment about how the original power supply works!

- John

[Nick]

Lovely as always!

Nick

On Saturday, 8 March 2014 16:42:43 UTC, Grahame Marsh wrote:

http://www.sgitheach.org.uk/strobotron.html

Enjoy
Grahame

[Quixotic Nixotic]

On 8 Mar 2014, at 16:42, Grahame Marsh wrote:

http://www.sgitheach.org.uk/strobotron.html

Enjoy
Grahame

Great work, as always.

I love this diagram. Now why can't I do layouts like that? I'd never make a mistake ever again.

 

John S

[threeneurons]

When I started reading Grahame's page, it reminded me of a project I once saw in a magazine article ,,, and further down the page, there it is ! Nice work !

I like those tubes.

[NeonJohn]

Nifty. I have two of the general radio Strobotachs that used the neon
tubes. I'm reversing direction on one. I'm putting solid state
internals in it with a microprocessor to read the big pot and set the
speed. That will get rid of the drift that plagues this model.

Best part is, I can fit the microprocessor without stripping out any of
the tube guts other than removing the tubes so the unit can be restored
to original if desired.

I also have a modern StroboTach. Now that thing is slick. I picked up
6 spare conducted arc strobe tubes for practically nothing at a hamfest.
NIB. I 'bout freaked when I saw the company now making the StroboTachs
charging $500 for a replacement flash tube.

John

On 03/08/2014 11:42 AM, Grahame Marsh wrote:
>
> http://www.sgitheach.org.uk/strobotron.html
>
> Enjoy
> Grahame
>

--
John DeArmond
Tellico Plains, Occupied TN
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PGP key: wwwkeys.pgp.net: BCB68D77

[Grahame Marsh]

Part of my interest was building something all-valve/tube. As always
with this sort of circuit the inefficiency of the rectifier is appalling.

But a microcontrolled version is on the agenda as the tubes do turn up
on ebay. The twin triode multivibrator is a bit eratic and can be hard
to set to get a near stationary object.. But it freezes the chuck of a
drill and the contents of the washing machine on fast spin. I hope to
add some videos to the webpage when I can sort out the additional
strobing effects between the digital camera and the flashing stroboscope.

NSP1 Ebay item 261169937643 - listed in the blurb as a "great audio
tube" hmm......

A photo of (or link to) the older strobotach you have would be of
interest; a google seach only turned up the modern digital versions that
I could recognise.

Grahame

[John Rehwinkel]

> NSP1 Ebay item 261169937643 - listed in the blurb as a "great audio tube" hmm......

Crisp glowing highs?

> A photo of (or link to) the older strobotach you have would be of interest; a google seach only turned up the modern digital versions that I could recognise.

I took a few pictures of mine:

Here's an overall view:

http://www.vitriol.com/images/tech/equipment/strobo-iso.jpg

You can see the glow of the flashtube, and the calibration reed below it, poking up through a hole in the reflector. It's driven by the mains frequency, so you can use it as a frequency reference.

Here are the dials:

http://www.vitriol.com/images/tech/equipment/strobo-dials.jpg

The large knob adjusts frequency, the smaller one sets range/function. There are a couple of screwdriver adjustments to tweak the frequency to match the dial reading.

Here's a top view:

http://www.vitriol.com/images/tech/equipment/strobo-top.jpg

It gives a view of the backlit frequency dial (driven by the knob), the handle, and the nameplate.

Here's the connector side:

http://www.vitriol.com/images/tech/equipment/strobo-connectors.jpg

And a head-on view:

http://www.vitriol.com/images/tech/equipment/strobo-front.jpg

Cheers,
John

[Instrument Resources of America]

This NSP1 has equivalents, (other numbers), which are as follows, SN4,
1D21, 631P1, CV220, R4100, and R4101. The 631P1 and the SN4 are
usually quite plentiful on Ebay. Ira.

[Instrument Resources of America]

I'm wondering if the missing center tap connection is internal to the
transformer, not brought out external to the transformer, and therefore
not shown on either the schematic, or wiring diagrams?? It would not
surprise me, although I would think that they should have shown it
anyway. Ira.

[John Rehwinkel]

> I'm wondering if the missing center tap connection is internal to the transformer, not brought out external to the transformer, and therefore not shown on either the schematic, or wiring diagrams?? It would not surprise me, although I would think that they should have shown it anyway.

I think it's just an omission in the schematic. The parts list shows a 235-0-235 transformer, so there should be a center tap.

- John

[Instrument Resources of America]

"Should be" is a bit of an understatement. LOL. There MUST be a center
tap or it will NOT work. Ira.

[Nick]

On Saturday, 8 March 2014 21:52:38 UTC, Nixcited delighted wrote:

Great work, as always.

I love this diagram. Now why can't I do layouts like that? I'd never make a mistake ever again.

I know you aren't a Windows man, John, but I find that Visio is a great tool for doing layouts - I've created a library of component parts for use when I'm restoring valve radios... I find it helps me greatly in the documentation process.

Nick

[Grahame Marsh]

I had assumed it was an error in the art work (schematic and wiring
diagrams)

Grahame

[Grahame Marsh]

John

Thank you for taking the photos and posting them. I particularly like
the little reed for calibration.

I was originally going to engrave the panel with high/low frequencies
but opted for a simple 0 - 10 as I was unsure how things would age; I
did realise the need for calibration adjustment pots in that case. I'm
also playing with the caps in the multivibrator to extend the range and
reduce the range overlap a bit. In practice I just plug it into a
frequency meter (I suppose I should build an all-valve nixie readout
frequency meter to go with it now).

Cheers Grahame

[John Rehwinkel]

> Thank you for taking the photos and posting them. I particularly like the little reed for calibration.

I thought it was clever too, and it works pretty well - it's easy to turn the dial until the strobe freezes the reed motion. That reflector you found was just the thing, it looks great.

> I was originally going to engrave the panel with high/low frequencies but opted for a simple 0 - 10 as I was unsure how things would age; I did realise the need for calibration adjustment pots in that case.

Indeed. The frequency window with the side-view dial would be hard to build, but it's easy to read and a nice touch in the commercial product.

> I'm also playing with the caps in the multivibrator to extend the range and reduce the range overlap a bit. In practice I just plug it into a frequency meter (I suppose I should build an all-valve nixie readout frequency meter to go with it now).

With an all-valve GPS disciplined reference! And the biggest valve of all will be the caesium fountain, right?

- Cheers,
John

[Grahame Marsh]

This is the reflector http://www.ebay.co.uk/itm/120982253359 (all sold
now). I cut the light fitting off and enlarged the hole to 32mm using a
sheet metal hole punch. The reflector makes the strobe! I would not
have proceeded with the build until I had got the right one. It is just
perfect.

All valve GPS Rx added to my to-do list. But I think a crystal
oscillator or mains frequency derived gate might be easier for the Mk
1. Perhaps a dekatron counter?

Grahame

[John Rehwinkel]

> This is the reflector http://www.ebay.co.uk/itm/120982253359 (all sold now).

Actually the seller relisted it and has four more now. I had guessed you'd picked up the reflector from a flashgun, those are much nicer, and have the handy flat perimeter with mounting holes.

> The reflector makes the strobe! I would not have proceeded with the build until I had got the right one. It is just perfect.

Indeed, an excellent find. I totally understand that mindset too, æsthetics are important.

> All valve GPS Rx added to my to-do list.

Hee!

> But I think a crystal oscillator or mains frequency derived gate might be easier for the Mk 1. Perhaps a dekatron counter?

That's the spirit! I still plan to breadboard some phantastron circuits and see if a) I can make them operate reasonably at megahertz frequencies, and b) if I can build a low power version with battery tubes.

I also wonder how fast I can drive one of those "crater" neon tubes - that might make an interesting high-frequency, low-brightness strobe.

- John

[Jon]

On Monday, March 10, 2014 12:51:03 PM UTC, Grahame Marsh wrote:

All valve GPS Rx added to my to-do list. But I think a crystal
oscillator or mains frequency derived gate might be easier for the Mk
1.  Perhaps a dekatron counter?

Always a good idea! :)

Jon.