Later on, I wanted
to build a "real" receiver with a loudspeaker but my knowledge of
radio science as well as the available money did not allow to
build a superhet one.
The owner of the local radio store gave me the schematic diagram of a low cost regenerative receiver, saying it was a "small wonder". It used the then popular battery tubes 1T4 and 3S4, powered by a 4.5 V (heater) and a 30 V batteries. It was a broadcast only receiver, covering the long waves and medium waves bands.
So I purchased the components, including the coil assembly, and build this receiver : I was delighted to hear many stations in the loudspeaker, especially when tuning the medium wave band at night.
Unfortunately the 30 V battery was expensive and its operating life rather short. Thus after some time, I began to think about another kind of receiver.
Years had gone by and many components of this receiver were used for other projects, until the remaining parts and the schematic diagram were put in a box and stored in the attic.
More than 50 years later, during a visit to the family house, I opened this box standing on a dusty shelf and found inside all these components : the coil assembly, the variable capacitor, the loudspeaker and its audio transformer and some resistors and capacitors.
I took the box back to my home, with the faint idea to rebuild this old receiver one day.
1. The rebuilding story.
The receiver schematic diagram is shown below : forgive for its poor quality and remember that it slept in a warm and dusty attic for more than 50 years.
The owner of the local radio store gave me the schematic diagram of a low cost regenerative receiver, saying it was a "small wonder". It used the then popular battery tubes 1T4 and 3S4, powered by a 4.5 V (heater) and a 30 V batteries. It was a broadcast only receiver, covering the long waves and medium waves bands.
So I purchased the components, including the coil assembly, and build this receiver : I was delighted to hear many stations in the loudspeaker, especially when tuning the medium wave band at night.
Unfortunately the 30 V battery was expensive and its operating life rather short. Thus after some time, I began to think about another kind of receiver.
Years had gone by and many components of this receiver were used for other projects, until the remaining parts and the schematic diagram were put in a box and stored in the attic.
More than 50 years later, during a visit to the family house, I opened this box standing on a dusty shelf and found inside all these components : the coil assembly, the variable capacitor, the loudspeaker and its audio transformer and some resistors and capacitors.
I took the box back to my home, with the faint idea to rebuild this old receiver one day.
1. The rebuilding story.
The receiver schematic diagram is shown below : forgive for its poor quality and remember that it slept in a warm and dusty attic for more than 50 years.
The first work was a complete
cleaning of the coil assembly with emphasis on the band switch. Next I
checked the resistors and capacitors and throw away the bad ones.
Trying to remember what the receiver looked like, I build an aluminum chassis with a wooden front panel. The tuning and regeneration variable capacitors, the coil assembly, the loudspeaker and the audio volume potentiometer were installed on this panel. The tube sockets and the audio transformer were mounted on the chassis and I wired the unit, using as many vintage parts as possible.
The pictures below show the complete receiver.
After connecting the receiver to 4.5 V and 30 V power supplies and the antenna jack to my 80 meters antenna, I switch it on and, a couple of seconds later (the time for the tubes to warm up), I tune across the long wave band and hear many stations. With a signal tuned in, rotating the regeneration control improves the reception, but this setting must be changed when tuning to another station .
On the medium wave band I can hear only one local station during daylight, but many others are coming at night, sometimes overloading the receiver.
Well, the "small wonder" is working again after sleeping for half a century in the attic !
Trying to remember what the receiver looked like, I build an aluminum chassis with a wooden front panel. The tuning and regeneration variable capacitors, the coil assembly, the loudspeaker and the audio volume potentiometer were installed on this panel. The tube sockets and the audio transformer were mounted on the chassis and I wired the unit, using as many vintage parts as possible.
The pictures below show the complete receiver.
Front view
Rear view
2. It works !After connecting the receiver to 4.5 V and 30 V power supplies and the antenna jack to my 80 meters antenna, I switch it on and, a couple of seconds later (the time for the tubes to warm up), I tune across the long wave band and hear many stations. With a signal tuned in, rotating the regeneration control improves the reception, but this setting must be changed when tuning to another station .
On the medium wave band I can hear only one local station during daylight, but many others are coming at night, sometimes overloading the receiver.
Well, the "small wonder" is working again after sleeping for half a century in the attic !