Hi,

all parts like double variable capacitor, ferrit antenna, oscillator coil, IF filter (colored red-yellow-white-black) are standard and can be taken from old and unused pocket radios – otherwise it will be noticed e.g. in my BOY’S RADIO coming up next because it uses nearly the same circuit but a “HF transformer”.

For the wiring I use since many decades the so-called Veroboard (wholes  with 2.54 or 5.08 mm distance all over the “PCB” with copper eyes for soldering), suitable sized and wired underneath:

This allows corrections and extensions without new design of the board. Critical circuits I use to test prior with the same material and with socket(s) for transistor(s) to select the best ones and to make additional experiments, here: using an output transformer for loudspeaker / second AF amplifier OR earphone usage only:

The ferrite antenna / capacitor-block is designed for multiple usage. The advantage: both components are adjusted for best reception once and can be used anywhere else. Because of the need of low impendance input in transistor radios the similar block for my tube superhets (reflex & “normal”, steel or pencil tubes) is quite vice versa, which means that the LC circuit has to be connected to grid 1 of the first tube, and the coupling part is for antenna input.

My circuits with the ZN414 (standard receiver and superhet applications) will come up, too… Be careful to use the ZN414 block because the IC only works with up to 1.5V (best: 1.3 V)!

Therefore I created a special block just to be sure that NEVER any problem will occur … and why not integrate all and ever required parts for usage in this block, too?!

I have a lot of stuff to introduce – please be patient 😉

… I forgot to explain that this circuit uses the converter twice (RF & AF) without IF amplifying – may be the amplification – depending on the location – is not sufficient: here are three versions of additional amplifier environments (sorry for the poor quality, but I haven’t found all the 3 old images on my actual PC – maybe a former HD crash – so I scanned a DIN A4 page with these printouts ):

It’s a 1-stage-amplifier as one Lectron block with the cable/plug (instead of the earphone / earpiece) with an input transformer (which appears around 1965 in Lectron patents!) , one Ge-transistor and different loudspeaker combinations. The middle one is a special one and contains a “transformer” with one coil and a tap at 50Ω; for the speaker and a stereo socket for stereo headphones of 2 x 32Ω; wired for mono parallel. The third one uses a universal transformer and a special “crossing” block.

Thanks for reading & don’t forget: all known and individual blocks at: http.//www.g-stabe.de/lectrony.htm

• This reply was modified 4 years, 10 months ago by Michael.
• This reply was modified 4 years, 10 months ago by Michael.
• This reply was modified 4 years, 10 months ago by Michael.
• This reply was modified 4 years, 10 months ago by Michael.

Hi,

yes – you are right, I could have made use of the HV transformer and the 2-stage amplifier, BUT: I use Lectron at first as a pre-testing tool before I build a “normal” (none-Lectron)  version or a new Lectron block.

In this case the limit of – total – 2 transistors was given by the BOY’S RADIO idea, more: see coming post. I had a lot of small transformers (and still have a couple of these) so to build a suitable Lectron transformer block is no problem. In this special case I had no free contact(s) for the AF output (or only diagonal, that’s bad…) so I first used the earphone socket. With a suitable plug + cable for a transformer-input it works, but I decided to built a separate block, so I don’t have to collect and place single blocks all over the ground plate just for testing another version – keep it simple!

Transformers: the first Lectron transformer from G.F. Greger was described in a patent applicant May 7th 1965 (# 1,228,081 Germany). Gerd Kopperschmidt realized it with blocks #2710 and #2712. Around 1970 Max Guerth built two of these (with tap !), and Harmut Birett in the 1970s for his Physics class. The cover images can be found in my “Electronic Lectron Card File” at line 415, 417 (Lectron RWO), 455, 456 (Max Guerth) and 604 (Hartmut Birett). The total amount is about 900 so it may be a help for positioning the thumb scroll bar.

Best,

Günther

• This reply was modified 4 years, 10 months ago by Michael.
• This reply was modified 4 years, 10 months ago by Michael.
• This reply was modified 4 years, 10 months ago by Michael.