Two transistor boys' radios - UK Vintage Radio Repair and Restoration Discussion Forum

Neil Purling · 4th Dec 2016, 11:31 pm

I happened to come across a mention of these curious pocket radios.
I am just wondering about how well the circuit works if anyone has knocked up one with modern parts.
Would it be a waste of effort to make up one given the actual RF and AF performance?

I have never made a reflexed circuit. I did make the Ladybird regenerative circuit & I have made radios with the Ferranti ZN414. Never a single transistor output stage.

Sideband · 4th Dec 2016, 11:49 pm

I came across a couple of these at school over 40 years ago. They were imported from Japan I think and with only two transistors were classed as 'toys' and avoided some sort of tax that was otherwise due on 'proper' radios. Performance was mediocre and really only 'local station'. They would probably struggle to give 50mW output and I think the distortion was quite high.

I think there are many better circuits around the web.

Here is information on one set the Coronet http://www.jamesbutters.com/coronetboysradio.htm

Boater Sam · 5th Dec 2016, 9:31 am

Ah, the ZN414, I threw a full box of them away when we moved 8 years ago,,,,,,,,fool that I am.

Neil Purling · 5th Dec 2016, 10:28 am

I think that maybe the intended market was the US where the country had a blanket of reasonably high power stations. In the UK the situation was probably rather different around 1960.

Has anybody got one of these in their collection that works? From looking at on-line sources it appears that in order for these radios to work properly they had to be used with the rod antenna. I am just wondering how one of these copes in the UK AM radio environment of today.

Herald1360 · 9th Dec 2016, 2:00 am

I built a set into a small drawer (instant case with handle) which used a reflex regen OC140. A little touchy to get just right, but when set up with a standard audio amp it was subjectively on a par with the usual superhet. A simpler audio stage (one transistor) would probably have been usable for quiet listening with the same approach.

Relating it back to valves, I had a commercial B7G battery set which gave a reasonable account of itself with only two valves.

One of these:

http://www.radiomuseum.org/r/ever_h.html

julie_m · 9th Dec 2016, 5:39 am

I think a set with just two valves was deemed to be "experimental" as opposed to home entertainment equipment, which would be considered "luxury goods" and attract a high rate of purchase tax.

A portable set with just two transistors would be a good kids' novelty, even if its performance left something to be desired. I suppose most of them ended up being thrown away -- but some owners might have been inspired to try making a better radio themselves.

And if one of them happened to be a girl, that would be the most fitting tribute to the sexist marketing people

60 oldjohn · 10th Dec 2016, 11:37 am

Quote:

Originally Posted by julie m

I suppose most of them ended up being thrown away -- but some owners might have been inspired to try making a better radio themselves.

Here is my boys set that did not succumb to either of the above.

John.

trsomian · 12th Dec 2016, 7:23 pm

I still have one, not in regular use anymore, but still works. In absolute terms it doesn't receive much, but for 2 transistors, is very good

Andrew2 · 12th Dec 2016, 11:22 pm

Quote:

Originally Posted by Neil Purling

I have never made a reflexed circuit. I did make the Ladybird regenerative circuit & I have made radios with the Ferranti ZN414. Never a single transistor output stage.

Reflexed radios can perform very well, especially if they also use regeneration. In the mid-60's I built a number of two and three transistor sets that combined the two techniques and with careful setting up they could receive those 'naughty nautical' stations quite well on their ferrite aerials even here in Manchester.
The later version of the Sinclair Micromatic used regeneration and reflex in a two transistor cct (the earlier one used three) and was a little cracker, especially when you consider its ferrite aerial was only about 25mm long!

trsomian · 13th Dec 2016, 1:14 pm

Comparing mine to the orange cased one shown by John, it is very similar, the case splits the same way, it is black and white, and the circuit board seems to have the same parts, but arranged differently. I even have the telescopic aerial to attach to it. I changed the volume control on mine, many years ago, because it was rather intermittent, and poor connection results in full volume (it loads the secondary of the driver transformer at low volume). Mine is labelled "Top Flight" and was given to me by an uncle in April 1967. Mine also has a little window in front of the volume knob showing a red wedge shaped spiral, getting wider as the volume is increased

Karen O · 13th Dec 2016, 5:17 pm

Charles Wenzel published a circuit for a ONE transistor radio (yes literally, and using a ferrite rod and not long wire aerial):

http://www.techlib.com/electronics/reflex.htm

As he mentions, the 'boys' radios' used a very similar circuit, the second transistor providing extra AF gain.

Top Cap · 13th Dec 2016, 6:21 pm

I am most intrigued by the MPSA18 with a DC Gain between 500 and 1500!
I may try to build one of my sea cadet radios with this in the front.
To save anyone searching for it, I will attach the JPEG, just hope it does not lose too much resolution....oops it has so
better still, download from http://www.g4cnh.com/public/Sea_Cadet_Tranny_radio.bmp

Les

trsomian · 13th Dec 2016, 11:42 pm

Just dug mine out and put a battery in it. Got 5 stations, two of which must have been R5, one "music" and another two speech towards the top of the band. Nothing earth shattering, but not bad for a radio that must be over 50 years old. One problem with mine is that there is only marginally enough room for a battery; the back doesn't quite fit on with a modern Duracell, and I used to have the same problem many years ago when it had a diet of "Flying Bomb" batteries, which I seem to remember a shop in St Albans had for 1/6 each, or two for half a crown. I could see the Brookmans Park transmitter from my bedroom window, so getting radios 1 and 4 was easy, R3 was rather weaker, and always had a bit of R4 in the background. Needless to say, this was before the radio changes of, I think, 1978

Jaffna Dog · 20th Dec 2016, 2:02 pm

Good to see a new design for home construction, have you tried submitting it to 'Practical Wireless', they still publish designs for 'wirelesses'

I have been researching receiver design recently , from the excellent 'American Radio History' website, with their archives of 'Radio Constructor' and 'Practical Wireless', and have printed out and bound a multi-volume compilation of transistor designs going back to the 1960's.

4th Dec 2016, 11:31 pm	#1
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,085	Two transistor boys' radios I happened to come across a mention of these curious pocket radios. I am just wondering about how well the circuit works if anyone has knocked up one with modern parts. Would it be a waste of effort to make up one given the actual RF and AF performance? I have never made a reflexed circuit. I did make the Ladybird regenerative circuit & I have made radios with the Ferranti ZN414. Never a single transistor output stage.

4th Dec 2016, 11:49 pm	#2
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,566	Re: Two transistor boys radios I came across a couple of these at school over 40 years ago. They were imported from Japan I think and with only two transistors were classed as 'toys' and avoided some sort of tax that was otherwise due on 'proper' radios. Performance was mediocre and really only 'local station'. They would probably struggle to give 50mW output and I think the distortion was quite high. I think there are many better circuits around the web. Here is information on one set the Coronet http://www.jamesbutters.com/coronetboysradio.htm __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman..... Last edited by Sideband; 5th Dec 2016 at 12:04 am.

5th Dec 2016, 9:31 am	#3
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Two transistor boys radios Ah, the ZN414, I threw a full box of them away when we moved 8 years ago,,,,,,,,fool that I am.

5th Dec 2016, 10:28 am	#4
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,085	Re: Two transistor boys radios I think that maybe the intended market was the US where the country had a blanket of reasonably high power stations. In the UK the situation was probably rather different around 1960. Has anybody got one of these in their collection that works? From looking at on-line sources it appears that in order for these radios to work properly they had to be used with the rod antenna. I am just wondering how one of these copes in the UK AM radio environment of today.

9th Dec 2016, 2:00 am	#5
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Two transistor boys' radios I built a set into a small drawer (instant case with handle) which used a reflex regen OC140. A little touchy to get just right, but when set up with a standard audio amp it was subjectively on a par with the usual superhet. A simpler audio stage (one transistor) would probably have been usable for quiet listening with the same approach. Relating it back to valves, I had a commercial B7G battery set which gave a reasonable account of itself with only two valves. One of these: http://www.radiomuseum.org/r/ever_h.html __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

9th Dec 2016, 5:39 am	#6
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Two transistor boys' radios I think a set with just two valves was deemed to be "experimental" as opposed to home entertainment equipment, which would be considered "luxury goods" and attract a high rate of purchase tax. A portable set with just two transistors would be a good kids' novelty, even if its performance left something to be desired. I suppose most of them ended up being thrown away -- but some owners might have been inspired to try making a better radio themselves. And if one of them happened to be a girl, that would be the most fitting tribute to the sexist marketing people __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

12th Dec 2016, 7:23 pm	#8
trsomian Hexode Join Date: Oct 2010 Location: Box End, Beds. UK. Posts: 271	Re: Two transistor boys' radios I still have one, not in regular use anymore, but still works. In absolute terms it doesn't receive much, but for 2 transistors, is very good

13th Dec 2016, 1:14 pm	#10
trsomian Hexode Join Date: Oct 2010 Location: Box End, Beds. UK. Posts: 271	Re: Two transistor boys' radios Comparing mine to the orange cased one shown by John, it is very similar, the case splits the same way, it is black and white, and the circuit board seems to have the same parts, but arranged differently. I even have the telescopic aerial to attach to it. I changed the volume control on mine, many years ago, because it was rather intermittent, and poor connection results in full volume (it loads the secondary of the driver transformer at low volume). Mine is labelled "Top Flight" and was given to me by an uncle in April 1967. Mine also has a little window in front of the volume knob showing a red wedge shaped spiral, getting wider as the volume is increased

13th Dec 2016, 5:17 pm	#11
Karen O Rest in Peace Join Date: Jul 2011 Location: Bridgnorth, Shropshire, UK. Posts: 787	Re: Two transistor boys' radios Charles Wenzel published a circuit for a ONE transistor radio (yes literally, and using a ferrite rod and not long wire aerial): http://www.techlib.com/electronics/reflex.htm As he mentions, the 'boys' radios' used a very similar circuit, the second transistor providing extra AF gain.

13th Dec 2016, 6:21 pm	#12
Top Cap Octode Join Date: Mar 2006 Location: Watford, Hertfordshire, UK. Posts: 1,270	Re: Two transistor boys' radios I am most intrigued by the MPSA18 with a DC Gain between 500 and 1500! I may try to build one of my sea cadet radios with this in the front. To save anyone searching for it, I will attach the JPEG, just hope it does not lose too much resolution....oops it has so better still, download from http://www.g4cnh.com/public/Sea_Cadet_Tranny_radio.bmp Les Attached Thumbnails __________________ Whether the Top Cap is Grid or Anode - touching it will give you a buzz either way! Last edited by Top Cap; 13th Dec 2016 at 6:34 pm.

13th Dec 2016, 11:42 pm	#13
trsomian Hexode Join Date: Oct 2010 Location: Box End, Beds. UK. Posts: 271	Re: Two transistor boys' radios Just dug mine out and put a battery in it. Got 5 stations, two of which must have been R5, one "music" and another two speech towards the top of the band. Nothing earth shattering, but not bad for a radio that must be over 50 years old. One problem with mine is that there is only marginally enough room for a battery; the back doesn't quite fit on with a modern Duracell, and I used to have the same problem many years ago when it had a diet of "Flying Bomb" batteries, which I seem to remember a shop in St Albans had for 1/6 each, or two for half a crown. I could see the Brookmans Park transmitter from my bedroom window, so getting radios 1 and 4 was easy, R3 was rather weaker, and always had a bit of R4 in the background. Needless to say, this was before the radio changes of, I think, 1978

20th Dec 2016, 2:02 pm	#14
Jaffna Dog Diode Join Date: Sep 2016 Location: Leicester, Leics. UK. Posts: 1	Re: Two transistor boys' radios Good to see a new design for home construction, have you tried submitting it to 'Practical Wireless', they still publish designs for 'wirelesses' I have been researching receiver design recently , from the excellent 'American Radio History' website, with their archives of 'Radio Constructor' and 'Practical Wireless', and have printed out and bound a multi-volume compilation of transistor designs going back to the 1960's.