Is this a one-valve receiver?

[Dillen_de]

I have had this in the back of a drawer for decades.
Not sure exactly what it is or where it came from, but it must have been among other things I've bought in a lot somewhere and I decided to keep it because it looked nice and exciting, and someone clearly put
a little time and love into it.

A DL96 valve, a few coils and capacitors, and I have no idea which lead would go to what, if I should ever feel the urge to find out what it can do.

The outer size of the plastic box is 85 x 60 x 40 mm

Not one of my own jobs, and most likely not one of another forum member either, so in reality perhaps not
exactly qualified for this category (no hard feelings if deleted) - just thought I'd show this nice little
piece of homebrew.
Perhaps someone can cast a little light on it?

Martin

[Heatercathodeshort]

Possibly but a lot of coils for a one valve radio. John.
PS Could it be a transmitter from a model boat or plane?

[paulsherwin]

The DL96 is an output valve, and while it could be used in a one valve radio, it would be a strange choice.

[joebog1]

It looks to me like a single tone radio receiver from a model plane. It uses the "power " valve to drive a rubber powered escapement to turn the rudder. I built something very similar when I was a kid about 60 years ago. The design came from Aircraft Modeller magazine I think. It was an english magazine that started way back in the late 20,s or so.

It worked by one push on the transmitter button drove the escapement left ( say ) another push on the button would unlock the escapement and drove it back to centre. Three button pushed drove it left first, then back to centre and right where it latched again. A further button push returned the escapement to centre and straightened the rudder.


Joe

[Silicon]

The small coil could be a ferrite aerial.

A variable transformer for tuning and a choke for an anode load?

[Dillen_de]

Thanks. Very interesting reading!
The coil lying parallel to the valve looks like a resistor with a coil wound around it.

Martin

[snowman_al]

I guess like Joe it is a remote control receiver for a boat or plane.
Super regenerative circuit and the DL92 / DL96 were popular choices before transistors.
Might even be an 'IVY' ? See here https://norcim-rc.club/Radio17.htm

[kalee20]

Almost certainly a model control transmitter, as others have said!

Bang-bang systems were simple and cheap, and most importantly, lightweight, in the era pre-IC's.

With clockwork escapements giving centre-left-centre-right-centre etc, the response time would have to be fairly rapid, if you wanted to steer left and the last operation had also been a left steer, you'd have to press-release-press to cycle through 'right' quickly enough to not steer significantly right before ending up with the desired left steer.

I'd therefore expect that LT would be left 'on' all the time, and keying would be by interrupting the HT.

There's 6 leads, which (assuming there weren't more and one is missing) would be LT + and -, HT + and -, aerial, and either key, or ground (the operator via the handle?).

If you can trace the circuit it would be super!

[Trevor]

can you make a circuit diagram for this looking at the unit it looks like a super regen
I think I cam mace out the quench coil etc.
I have long been fascinated by this kind of thing

[joebog1]

kalee, Its a receiver NOT the transmitter. One doesnt normally have a rudder on a transmitter. Not even in blighty.
Thanks to the snowman for that excellent link!!!. I have been radio modelling for as long as I have been doing electronics. Your link brings back memories from my brain dungeon that I had forgotten.


Joe

[kalee20]

It's the valve choice which led me (same as Paul in post #3) to suggesting a transmitter rather than a receiver - a self oscillating single channel transmitter.

I recall seeing a transmitter design by F G Rayer in Practical Wireless, 1950's, using a single DL92.

[joebog1]

As I remember ( and its over 60 years ago ) my transmitter used a 3S4. That was an audio bottle from battery sets back in the day.
http://www.r-type.org/exhib/abh0277.htm

I cannot remember anything else, EXCEPT that the receiver ( as I call it ) looked very similar to what the OP has shown in post #1.
I do remember it was power hungry and my six bob a fortnight was hard pressed to buy diesel fuel
( ether and castor oil ) and batteries. NOT to mention more balsa to make matches from when my piloting skills didnt match my ego!!.
THAT was a long time ago!!.

Joe

P.S. my piloting skills havent changed, except now I need buy more carbon fibre.

[HamishBoxer]

Is the valve strapped as a triode?

[Dillen_de]

I'll see if I can trace a schematic out of it.

Martin

[G6Tanuki]

Having played-around with similar super-regen 27MHz model-radios in the past I will be intrugued to see the circuit.

My brother was always the 'aivionics' side, building crazy Nitromethane-fuelled pulse-jet stuff; I did the radios, just at the time when transistors were becoming affordable; though an OC170 was expensive it didn't have a fragile filament that failed-when-you-crashed! I remember building a transmitter using a 6J6 double-triode valve that I powered from a car-battery and a vibrator-unit from some long-dead car-radio: it produced enough RF on 27MHz [plus or minus a Megahertz or so] to light a 12-volt 5-watt car sidelight bulb. Then we moved on to resonant-reeds, pot-cores and 'discriminators' that got us proportional control by a joystick that wiggled a bit of ferrite-rod into the middle of an audio-frequency coil excited by an OC72]

[Trevor]

That sounds very exciting and is just where I would like to b A small valve radio controlled boat would be a dream come true

[Al (astral highway)]

Originally Posted by Dillen_de

Thanks. Very interesting reading!
The coil lying parallel to the valve looks like a resistor with a coil wound around it.

Choke? That is likely a 1 Megohm or similar high value resistor that is just used as a handy coil former. Useful thing to do if you want a choke but the wire gauge needs some support.

Looks like the builder was following point-to-point instructions rather than experienced.

[Dillen_de]

All correct. A second look reveals, that the resistor itself is not connected to anything.

Martin

[joebog1]

It wouldnt really matter, MIGHT reduce Q a bit I suppose, but it was common years ago. 1 meg or above was the recommended value.
100 turns wound on one million ohms or above is close to a dead short.
I dont know much about the higher frequencies, but the radio I built in probably 1962 or '62 was only around 1.8 megahertz or so. It was never specified, and in any case was so low powered it only covered the playing field where we used to fly our models.. By playing field I mean football or cricket ground. ( I dont know how big they are, I have NEVER played sport ).
Was at best a couple of hundred metres.

Joe

[davidw]

This thread has rung a bell with me, I think it may be similar to the attached from a PW booklet of 1961 "25 selected Circuits" . I remember building it (as a 12 year old). My friends dad was manager of the local "Currys" and got us a couple of 1T4 valves hence the amended pinout diagram! I Don't think either of us managed to make it work very well! I don't make such a mess with flux nowadays!
Mods..if this attachment breaks any rules please feel free to remove..