The first circuit you ever built... - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Refugee · 14th Nov 2016, 3:04 am

My first success was a transistor tester I designed myself with a metal canned 741 in it.
The idea was to measure HFE at several collector currents to produce a poor mans graph for matching. I still use it and even extend the collector current ranges by adding an external collector current from a bench power supply. I was using it a couple of years ago for matching huge power transistors at a couple of amps.
There is nothing available that can do this without either spending a fortune or taking up a huge amount of badly needed space. It still lives.

My only surviving magazine project also still survives and is also still in regular use. It is the ETI sweep oscillator. It was troubled with stability problems if the faster chips were used and this was fixed last time I gave it a service. There was a decoupling capacitor or two missing from the original design and with no holes in the board they went on the track side. Those capacitors have a life time guarantee that the leads won't snap off because they have none.

fetteler · 14th Nov 2016, 3:22 am

Quote:

Originally Posted by G6Tanuki

I was around 9 when I built this little amplifier.

That's a truly lovely little thing to have made at such a tender age. Superb! Well done

I was well into balsa wood and tissue paper at age 9 years! I guess I was about 13 or 14 when I first started on real electronics, sadly I can't recall the first thing I ever made but pre - dating that though, I can remember the first thing I ever repaired and modified. It was a pair of old valve radios that I 'fixed' by replacing the waxy coupling capacitors and then used as amplifiers in a stereo record player.

Eeeehhh, happy days!!!!

Steve.

goodvibrations · 14th Nov 2016, 4:35 am

Quote:

Originally Posted by g6tanuki

digging back through a box of junk, i came across the first 'serious' bit of electronics i built - a little push-pull audio amp. All 200-milliwatts of it....

Oc71 driver transistor, a pair of oc78 as the output stage, lt44 and lt700 transformers. I remember buying all the bits at walton's in wolverhampton.

This dates back to around 1969. It still works!

the first circuit i ever built and designed still works 35 years later - it was an audio amplifier with bass treble vol etc and i over engineered everything to last and it did. Japanese caps, good toroidal etc, the secret to its success was in the power supply i used rubicon caps and elna - still work today

crusher19860138 · 14th Nov 2016, 8:27 am

Quote:

Originally Posted by G6Tanuki

Digging back through a box of junk, I came across the first 'serious' bit of electronics I built - a little push-pull audio amp. All 200-milliwatts of it....

OC71 driver transistor, a pair of OC78 as the output stage, LT44 and LT700 transformers. I remember buying all the bits at Walton's in Wolverhampton.

This dates back to around 1969. It still works!

Waltons in Wolvo was a fantastic shop,shame it's gone,I made a transistor radio with parts from Waltons,the one in the ladybird book making a transistor radio,it gave me hours of enjoyment as a young man.

G4_Pete · 14th Nov 2016, 9:18 am

Hi,
One early memory was a circuit which lit a neon from a battery, intended as an on /off indicator for a battery radio, I remember hand winding hundreds of turns of fine wire I got from disecting a car HT coil. I remember it worked briefly and then never worked again!! This was published in radio constructor or similar vintage magazine. I think the artical was called " 2mA neon ... " . If anyone can recall or can point me in the direction of a copy of the artical it would be interesting to see again after all these years. ( I have searched but not found it)

Pete

raditechman · 14th Nov 2016, 9:43 am

Like hamishboxer apart from crystal sets my first major build was a Top Band AM rig.
I was aged 16 then and several radio interested chums also built rigs. AM 160m was very active back then. I had an 807 as the PA, EL84 driving the modulation transformer, an EF80 VFO using a Hartley oscillator. Crystal mike! A couple of my chums got caught!
We all later became licenced amateurs and I still keep in touch with most of them.
In fact one of them called to see me yesterday (a G3 now) and has let me have a Trio 9R59d as that was the first "proper" receiver I had.

John

Malcolm G6ANZ · 14th Nov 2016, 10:21 am

I can't remember the first circuit I built that worked. The first serious item was a 2M AM transmitter and modulator. All valve, apart from the VFO, with a V0/310 driving a modulated v0/640 final. The modulator was a pair of KT88's. Built on two separate 12"x9"chassis and separate PSU.
Worked exceedingly well with a B40 RX.
Malcolm

bluepilot · 14th Nov 2016, 12:10 pm

I can't remember whether it was the first but certainly an early circuit I built was a high frequency power supply for my model railway. I got the circuit from Railway Modeller. Must have been about 1970. It was a valve-based 100kHz oscillator, the idea being that with a few capacitors it would be possible to have lighting in the carriages even when the train was standing still. The second harmonic of 100kHz is 200kHz which was also the light programme and with quite a few yards of track it radiated quite well. The result was no-one in the area could receive the light programme. Luckily I realised what was going on before anyone turned up to investigate the interference.

P.Pilcher · 14th Nov 2016, 1:29 pm

Having wired up batteries and bulbs with bits of fusewire since I was knee high to a grasshopper, I decided that my first real circuit had to be mains driven. Accordingly, at the tender age of about 9 I acquired a tag strip, resistor of appropriate value and a neon lamp. These were connected in series to a plug with a 3 amp fuse and with much trepidation, the plug was inserted into a mains socket.... It worked!! This was 1956.

P.P.

Paul_RK · 14th Nov 2016, 1:44 pm

My first circuits: oh dear. There was a neon metronome. thrown together in an Ever Ready Sky Baronet case, where I'm almost certain I pressed a Telsen Radiogrand audio transformer - well, the ratio, 3:1, was pretty much correct - into service to power the thing, and to the transformer's credit it never protested against its mains input. Then an audio amplifier using salvaged TV parts, to a design in Practical Television, which worked sort of tolerably: I only remember the output valve being a PL81. I never did have any sort of constructional kit, or buy many new components, when radios and TVs from the local auction starting at two shillings apiece seemed much more cost-effective, but preserving and restoring them always held more attraction for me than building things.

Paul

clay shooter · 14th Nov 2016, 2:11 pm

Mine was the pw seeking metal detector from around 1977, I tried to remake one several years ago but couldn't get this one to work, think it was a fault with my first attempt of circuit board etching !

peterpiper · 14th Nov 2016, 2:12 pm

Hi All, My first effort was a one transistor (red spot) amplified crystal set bought as a kit from "the wee shop in Stockwell st" about 1961.Later known as RME. The kit consisted of a Thick cardboard panel, glossy white with basic MW dial markings and a 500pf solid dielectric cap. 2 holes Ae and Earth and 2 for headphones. Does anyone else remember it? Ive searched the net and cant find a trace. The only part I have left of it is what is now known as a chicken head knob. Its about to find a new use on a Parker P36 guitar I just bought !

Peter

cathy_vintage · 14th Nov 2016, 2:17 pm

Ash here:- Mine was a crystal set but using a germanium diode instead of galena crystal and cat's whisker. The design was in a book of schoolboy projects which also had the construction plans for a boomerang in it, which was brilliant too until it got stuck in a tree. The 'crystal' set (best signal was from pirate 'Radio 270') prompted me to get a Philips EE kit the same Christmas and I bought the add on kit as soon as the shops re-opened after Christmas. What a brilliant idea that Philips kit was and cunning marketing to get you hooked on the basic set, so that you had to immediately save up your pocket money for the add-on kit.

Paul_RK · 14th Nov 2016, 2:32 pm

Quote:

Originally Posted by Paul_RK

Then an audio amplifier using salvaged TV parts, to a design in Practical Television...

And little by little the horror returns, I can see it now in my mind's eye: assembled on a perspex implosion screen (it was easy to drill, I didn't fancy metalwork), screwed to the lid from an HMV add-on 78 player which acted as its plinth, control knobs (ex-Cossor Melody Maker) in front, valves and mains dropper behind. I must have been 12 or thereabouts, and though it wasn't far from being my first constructional project it wasn't very far either from being my last.

llama · 14th Nov 2016, 3:03 pm

Based on an earlier crystal set, probably my first useful item was a radio jack (crystal set, fixed on Light Programme) built on the back of the innards of a jack plug. Used to feed my Stern's reel to reel.

And from a Practical Wireless article, an electronic organ using a 6SN7 and a 6V6. The keyboard used drawing pin contacts stuck in the ends of piano keys from a scrap upright piano. Those contacts were never very good leading to a persisting note (the contacts were in series so any broken contact created a note). The other day I came across the chassis of it (the keys haven't survived) and that reminded me that that, and most of my projects, simply used a heater transformer and rectified mains.
Graham

mole42uk · 14th Nov 2016, 4:26 pm

Actually, my first project was a one-valve radio kit that was advertised as "needs no soldering". It never worked either.

The Philips EE20 transistor radio was next.

Andrew2 · 14th Nov 2016, 5:07 pm

Apart from simple batteries/wires/bulbs type things, I think my first project was a crystal set. I built a few of these and got the radio bug with a vengeance! Next came a Tri-onic electronics kit which included a one transistor receiver and then I tried for ages to build my own. Finally succeeded and then went for more and more complex radios and ended up with a 3-transistor one with reflex and regeneration. With care it could drag in the weak signals from the naughty pirate ships and I was delighted! All this took place from about 1960 to 1967 when I was at school. Happy days!

Aerodyne · 14th Nov 2016, 5:28 pm

1954. I was 11 when I built the PW 'modern 1-valver'. That dates me well and truly. I could not afford the actual coil used so I obtained a rather ancient replacement, used a WD valve and a pair of prewar headphones that I'd been given. Some components were 'saved' from an old radio chassis I'd begged from a local firewood merchant.
Eeh, but we 'ad it 'ard in them days.
Tony

Panrock · 14th Nov 2016, 5:38 pm

Two possibles here for me:

The first was a resistor, capacitor, neon and 90v battery... to make a winking neon. I later used this same arrangement to provide the sawtooth for a 3-inch VCR139A televisor project. By then I had discovered Henry's Radio....

The other one was a carbon 'arc lamp' consisting of two pencils across the mains. Once the arc was 'struck' the pencils caught fire. I dropped them in a panic and scorched the Drawing Room carpet. My parents weren't best pleased.

Steve

kellys_eye · 14th Nov 2016, 6:30 pm

I recall having a visit from a 'nice' detective whilst sat waiting in my mum's car during her shopping trip. I was only building some projects from the electronics kit I'd received that Christmas..... early 1970's. A concerned passer-by had reported me to the local Police Station !!

I'd probably get the same attention if I did the same today!

14th Nov 2016, 3:04 am	#21
Refugee Dekatron Join Date: Apr 2012 Location: Worksop, Nottinghamshire, UK. Posts: 5,554	Re: The first circuit you ever built... My first success was a transistor tester I designed myself with a metal canned 741 in it. The idea was to measure HFE at several collector currents to produce a poor mans graph for matching. I still use it and even extend the collector current ranges by adding an external collector current from a bench power supply. I was using it a couple of years ago for matching huge power transistors at a couple of amps. There is nothing available that can do this without either spending a fortune or taking up a huge amount of badly needed space. It still lives. My only surviving magazine project also still survives and is also still in regular use. It is the ETI sweep oscillator. It was troubled with stability problems if the faster chips were used and this was fixed last time I gave it a service. There was a decoupling capacitor or two missing from the original design and with no holes in the board they went on the track side. Those capacitors have a life time guarantee that the leads won't snap off because they have none. Attached Thumbnails

14th Nov 2016, 9:18 am	#25
G4_Pete Hexode Join Date: Feb 2014 Location: Southampton, Hampshire, UK. Posts: 419	Re: The first circuit you ever built... Hi, One early memory was a circuit which lit a neon from a battery, intended as an on /off indicator for a battery radio, I remember hand winding hundreds of turns of fine wire I got from disecting a car HT coil. I remember it worked briefly and then never worked again!! This was published in radio constructor or similar vintage magazine. I think the artical was called " 2mA neon ... " . If anyone can recall or can point me in the direction of a copy of the artical it would be interesting to see again after all these years. ( I have searched but not found it) Pete

14th Nov 2016, 9:43 am	#26
raditechman Heptode Join Date: Feb 2007 Location: West London, UK. Posts: 867	Re: The first circuit you ever built... Like hamishboxer apart from crystal sets my first major build was a Top Band AM rig. I was aged 16 then and several radio interested chums also built rigs. AM 160m was very active back then. I had an 807 as the PA, EL84 driving the modulation transformer, an EF80 VFO using a Hartley oscillator. Crystal mike! A couple of my chums got caught! We all later became licenced amateurs and I still keep in touch with most of them. In fact one of them called to see me yesterday (a G3 now) and has let me have a Trio 9R59d as that was the first "proper" receiver I had. John

14th Nov 2016, 10:21 am	#27
Malcolm G6ANZ Octode Join Date: Feb 2006 Location: Bristol, UK. Posts: 1,042	Re: The first circuit you ever built... I can't remember the first circuit I built that worked. The first serious item was a 2M AM transmitter and modulator. All valve, apart from the VFO, with a V0/310 driving a modulated v0/640 final. The modulator was a pair of KT88's. Built on two separate 12"x9"chassis and separate PSU. Worked exceedingly well with a B40 RX. Malcolm

14th Nov 2016, 12:10 pm	#28
bluepilot Heptode Join Date: Feb 2010 Location: Duffort, Gers, France Posts: 714	Re: The first circuit you ever built... I can't remember whether it was the first but certainly an early circuit I built was a high frequency power supply for my model railway. I got the circuit from Railway Modeller. Must have been about 1970. It was a valve-based 100kHz oscillator, the idea being that with a few capacitors it would be possible to have lighting in the carriages even when the train was standing still. The second harmonic of 100kHz is 200kHz which was also the light programme and with quite a few yards of track it radiated quite well. The result was no-one in the area could receive the light programme. Luckily I realised what was going on before anyone turned up to investigate the interference. __________________ Stuart The golden age is always yesterday - Asa Briggs

14th Nov 2016, 1:29 pm	#29
P.Pilcher Pentode Join Date: Jan 2010 Location: Lichfield, Staffs, UK. Posts: 150	Re: The first circuit you ever built... Having wired up batteries and bulbs with bits of fusewire since I was knee high to a grasshopper, I decided that my first real circuit had to be mains driven. Accordingly, at the tender age of about 9 I acquired a tag strip, resistor of appropriate value and a neon lamp. These were connected in series to a plug with a 3 amp fuse and with much trepidation, the plug was inserted into a mains socket.... It worked!! This was 1956. P.P. __________________ "Ohm's law rules here" - Oxygen free speaker cable not required! (Quote: Quad Service lab)

14th Nov 2016, 1:44 pm	#30
Paul_RK Dekatron Join Date: Nov 2003 Location: Fakenham, Norfolk, UK. Posts: 4,259	Re: The first circuit you ever built... My first circuits: oh dear. There was a neon metronome. thrown together in an Ever Ready Sky Baronet case, where I'm almost certain I pressed a Telsen Radiogrand audio transformer - well, the ratio, 3:1, was pretty much correct - into service to power the thing, and to the transformer's credit it never protested against its mains input. Then an audio amplifier using salvaged TV parts, to a design in Practical Television, which worked sort of tolerably: I only remember the output valve being a PL81. I never did have any sort of constructional kit, or buy many new components, when radios and TVs from the local auction starting at two shillings apiece seemed much more cost-effective, but preserving and restoring them always held more attraction for me than building things. Paul

14th Nov 2016, 2:11 pm	#31
clay shooter Pentode Join Date: Jul 2014 Location: Northamptonshire, UK. Posts: 135	Re: The first circuit you ever built... Mine was the pw seeking metal detector from around 1977, I tried to remake one several years ago but couldn't get this one to work, think it was a fault with my first attempt of circuit board etching ! __________________ If it ain't bust don't fix it

14th Nov 2016, 2:12 pm	#32
peterpiper Tetrode Join Date: Jul 2016 Location: Renfrew, Renfrewshire, UK. Posts: 93	Re: The first circuit you ever built... Hi All, My first effort was a one transistor (red spot) amplified crystal set bought as a kit from "the wee shop in Stockwell st" about 1961.Later known as RME. The kit consisted of a Thick cardboard panel, glossy white with basic MW dial markings and a 500pf solid dielectric cap. 2 holes Ae and Earth and 2 for headphones. Does anyone else remember it? Ive searched the net and cant find a trace. The only part I have left of it is what is now known as a chicken head knob. Its about to find a new use on a Parker P36 guitar I just bought ! Peter

14th Nov 2016, 2:17 pm	#33
cathy_vintage Pentode Join Date: Sep 2016 Location: Willerby, East Yorkshire, UK. Posts: 191	Re: The first circuit you ever built... Ash here:- Mine was a crystal set but using a germanium diode instead of galena crystal and cat's whisker. The design was in a book of schoolboy projects which also had the construction plans for a boomerang in it, which was brilliant too until it got stuck in a tree. The 'crystal' set (best signal was from pirate 'Radio 270') prompted me to get a Philips EE kit the same Christmas and I bought the add on kit as soon as the shops re-opened after Christmas. What a brilliant idea that Philips kit was and cunning marketing to get you hooked on the basic set, so that you had to immediately save up your pocket money for the add-on kit.

14th Nov 2016, 3:03 pm	#35
llama Octode Join Date: Jun 2006 Location: St Osyth, Nr Clacton, Essex, UK. Posts: 1,482	Re: The first circuit you ever built... Based on an earlier crystal set, probably my first useful item was a radio jack (crystal set, fixed on Light Programme) built on the back of the innards of a jack plug. Used to feed my Stern's reel to reel. And from a Practical Wireless article, an electronic organ using a 6SN7 and a 6V6. The keyboard used drawing pin contacts stuck in the ends of piano keys from a scrap upright piano. Those contacts were never very good leading to a persisting note (the contacts were in series so any broken contact created a note). The other day I came across the chassis of it (the keys haven't survived) and that reminded me that that, and most of my projects, simply used a heater transformer and rectified mains. Graham __________________ Half my stuff is junk - trouble is, I don't know which half!

14th Nov 2016, 4:26 pm	#36
mole42uk Nonode Join Date: Aug 2010 Location: Resolven, Wales; and Bristol, England Posts: 2,612	Re: The first circuit you ever built... Actually, my first project was a one-valve radio kit that was advertised as "needs no soldering". It never worked either. The Philips EE20 transistor radio was next. __________________ Richard Index: recursive loop: see recursive loop

14th Nov 2016, 5:07 pm	#37
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,038	Re: The first circuit you ever built... Apart from simple batteries/wires/bulbs type things, I think my first project was a crystal set. I built a few of these and got the radio bug with a vengeance! Next came a Tri-onic electronics kit which included a one transistor receiver and then I tried for ages to build my own. Finally succeeded and then went for more and more complex radios and ended up with a 3-transistor one with reflex and regeneration. With care it could drag in the weak signals from the naughty pirate ships and I was delighted! All this took place from about 1960 to 1967 when I was at school. Happy days! __________________ Andy G1HBE.

14th Nov 2016, 5:28 pm	#38
Aerodyne Octode Join Date: Jun 2004 Location: Hampton Vale, Peterborough, UK. Posts: 1,698	Re: The first circuit you ever built... 1954. I was 11 when I built the PW 'modern 1-valver'. That dates me well and truly. I could not afford the actual coil used so I obtained a rather ancient replacement, used a WD valve and a pair of prewar headphones that I'd been given. Some components were 'saved' from an old radio chassis I'd begged from a local firewood merchant. Eeh, but we 'ad it 'ard in them days. Tony

14th Nov 2016, 5:38 pm	#39
Panrock Nonode Join Date: Feb 2005 Location: Worcestershire, UK. Posts: 2,534	Re: The first circuit you ever built... Two possibles here for me: The first was a resistor, capacitor, neon and 90v battery... to make a winking neon. I later used this same arrangement to provide the sawtooth for a 3-inch VCR139A televisor project. By then I had discovered Henry's Radio.... The other one was a carbon 'arc lamp' consisting of two pencils across the mains. Once the arc was 'struck' the pencils caught fire. I dropped them in a panic and scorched the Drawing Room carpet. My parents weren't best pleased. Steve __________________ https://www.radiocraft.co.uk

14th Nov 2016, 6:30 pm	#40
kellys_eye Octode Join Date: Jan 2014 Location: Oban, Scotland, UK. Posts: 1,129	Re: The first circuit you ever built... I recall having a visit from a 'nice' detective whilst sat waiting in my mum's car during her shopping trip. I was only building some projects from the electronics kit I'd received that Christmas..... early 1970's. A concerned passer-by had reported me to the local Police Station !! I'd probably get the same attention if I did the same today!