Identifying unknown items

[Julesomega]

Thanks Brian: I've somehow got a few, looking for a home in a museum

Originally Posted by Radio Wrangler

Carbon mikes are truly 'orrible things, so bringing one back to life to life has no tangible benefit other than slaking curiosity

Sure, but somewhere there's a panel missing one. Anyway, it's in the brass recycling bucket now

[Julesomega]

What could this be? Out of one of the TV PCBs I was carefully dismantling with an angle grinder. Multimeter says open circuit, component tester says unknown or faulty
I need to know which box it goes in, unless anyone is looking for one

[barrymagrec]

0.1uf 250 volt cap - probably polyester.

[Julesomega]

Oh dear, I really wish I hadn't posted this. The PCB even shows "C76"
At least, it's shown up a small issue with the component tester which I am now fixing. I really wanted it to be a high quality high value resistor

[Julesomega]

Does anyone recognise this grille? I'm hoping it might be out of a vintage CB radio, 151×93mm, made of lots of aluminium holes and spun-polished. I'd like to re-unite it with something

[McMurdo]

did you find out about your item in post 1?
A generator AVR springs to mind, the lockable pot being the output voltage maybe?

[Julesomega]

I've found nothing further on the power assembly with the thyristor, Kevin. What sort of generator were you thinking of?

[McMurdo]

an alternator attached to an internal combustion engine for the purposes of producing a temporary mains supply

[llama]

The 2-pin connectors in post #12 look like these:

https://www.radiomuseum.co.uk/R1147.html

(scroll 2/3 of the way down)
Graham

[Julesomega]

Thank you Graham! I inherited a few bits from an R1147 which my schoolmate had decided to pull apart. I marvelled at the equal mix of tube technology and gearing and decided there and then I was going to get involved in radio

A real radio has some gears in it

[Julesomega]

What do we know about a Majorette Mk II B Flash Head Controller made by Clive Courtnay & Co. from Dorking? It seems to control a dangerous quantity of Joules which can be triggered by cameras or a push switch

It contains 6 × 400µF electrolytics rated at 500V and connected in various combinations with large switches. There is a bank of 48H8 devices which look like metal oxide rectifier piles, and there is one thermionic device, a 2D21 which is a "small thyratron"

Would I be right to think this was for remote synchronisation of some sort of flash lamps in studio photography? What sort of lamp would require all those Joules? I was hoping the transformer might serve for a power supply for a comms receiver, but it looks like the voltages will be too high

One teasing little detail is the fuse which is shorted out by the rear panel: this looks like an oversight as there are no fuses inside to warrant a spare

[Andrew B]

Originally Posted by Julesomega

What could this be? Out of one of the TV PCBs I was carefully dismantling with an angle grinder. Multimeter says open circuit, component tester says unknown or faulty
I need to know which box it goes in, unless anyone is looking for one

Don't let us deflect it's trajectory to the recycle bin

[Jon_G4MDC]

Grille in Post 25 looks very Philips Cassette recorder to me.
A bigger one than EL3302...?

[duncanlowe]

Originally Posted by Julesomega

What do we know about a Majorette Mk II B Flash Head Controller made by Clive Courtnay & Co. from Dorking? It seems to control a dangerous quantity of Joules which can be triggered by cameras or a push switch

It contains 6 × 400µF electrolytics rated at 500V and connected in various combinations with large switches. There is a bank of 48H8 devices which look like metal oxide rectifier piles, and there is one thermionic device, a 2D21 which is a "small thyratron"

Would I be right to think this was for remote synchronisation of some sort of flash lamps in studio photography? What sort of lamp would require all those Joules? I was hoping the transformer might serve for a power supply for a comms receiver, but it looks like the voltages will be too high

One teasing little detail is the fuse which is shorted out by the rear panel: this looks like an oversight as there are no fuses inside to warrant a spare

It certainly reminds me of the times they did school photographs. There would be a large flash unit remoter from the camera that looked like a large angle poise, with an umbrella fitted. There's also a setting on your unit for setting the phototransistor sensitivity presumably as a trigger from the cameras flash.

[chriswood1900]

Originally Posted by Julesomega

Would I be right to think this was for remote synchronisation of some sort of flash lamps in studio photography? What sort of lamp would require all those Joules?

What you have is the power supply for a 4 head professional studio flash system. Quite old and now superseded by stand alone units. I believe Courtenay units were latterly sold by Patterson who are well known for photographic accessories. It would not be much use without compatible flash heads which as well as the flash units usually contained a 150 watt photo bulb for focus.
As regards the transformer I would be tempted to take out the surrounding circuits and take some voltage readings and work from there, you never know it might have some useable windings, it highly unlikely that it would be of any value or safe for photo flash.

[Julesomega]

Thank you Chris. You have absolved me of any curatorial duties so I will remove the transformer for assessment

I'm still curious as to the characteristics of those 48H8 devices

[Julesomega]

Originally Posted by chriswood1900

.. the power supply for a 4 head professional studio flash system. Quite old and now superseded by stand alone units. I believe Courtenay units were latterly sold by Patterson who are well known for photographic accessories. It would not be much use without compatible flash heads which as well as the flash units usually contained a 150 watt photo bulb for focus

As if to confirm Chris, a Cortney Lamp Tester has just rolled across my path: won't be needing that though

[Julesomega]

What is this PSU unit? Very distinctive, with its vibrators, metal oxide rectifiers, mains transformer, paper capacitors, and three substantial chokes. Mains input from 100-250V can be selected by taps, but what is the DC input, what are the outputs, and is the vibrator and its spare, synchronous or non-sync?

[robinshack]

That colour/finish on the choke underneath looks similar to Pye Telecom products of 50s and 60s. Some (only later ones?) had a Pye transfer on them.
May be an avenue of exploration?
Rob

[Radio Wrangler]

The flash heads for that Courtney unit will contain three things

1) A xenon flash tube, which gets connected straight back to a big capacitor in the unit. The HT is on it full time. The HT alone in not enough for the tube to initiate ionisation in the tube. The tube will have an external electrode which needs a low energy spike of a couple of kV to fire the xenon tube. The Xenon tube then runs until the main capacitor in the box you have falls below its drop-out voltage, then the mains transformer, rectifier and a series resistor start re-charging it. Photographers want a fast re-charge time, but the charging current must be low enough to let the xenon tubes drop out. The flash power may be changed by selecting taps on the mains transformer, or by switching capacitors in and out of circuit.

2) A trigger transformer.... the camera shutter contacts trigger the thyratron (modern cameras with a transistor that turns on for triggering flashes will be damaged by a flash of this era) the thyratron pulses the primaries of one trigger transformer in each flash head. The high voltage secondaries make the high voltage pulse for the trigger electrode on each head's flash tube.

3) A socket for a boring old filament bulb, mains powered via the 'Modelling light' switch on the power supply box. Modelling lights allow models to be moved around to compose the photo to be shot and to represent where the flash light will go. It's just bright enough to focus with a wide-open lens aperture (wide open is also when the lens depth of focus is minimal, so focusing is more critical, which is convenient)

Flash heads get fitted with reflectors, umberella reflectors, barn door flaps and all sorts of light shaping accessories.

Using four heads in a studio is not exceptional. One for the main amount of light, a second from a different angle to fill in shadows, one behind the model to light the background, and one from above to put some shine on the model's hair... and all for a simple portrait!

Units like this are still made. Many have a rechargeable battery and an inverter, and a trigger input dainty enough to not destroy cameras. The big British maker, Bowens, has recently gone out of business.

The same sort of stuff, on a smaller scale is in the sort of flash units used on top of a camera (or built in) LED flashes are available, but not yet competing with the power of a xenon discharge tube. On-camera flashes have grown to challenge the studio jobs, so nowadaus you may well find a monster on-camera sort of flash clipped to the focal point of a brolly reflector or a soft box. These things can be under radio control from the camera touchscreen, and the camera screen can even mirror the info back from each of several flashes' own screens. But this is pricey £500 for each flash, and Nikon want £200 for the tiddley little radio interface to screw to the camera. Studio flash gear is in about the same price range.

So, your unit was once the heart of a pretty serious studio lighting system. Today's systems have added a few electronic bells and whistles, but the old thing with its matching heads would still do the job today, with a little interface box to handle the difference in trigger voltages at the camera.

David