567
Item nr.
Largest Matchbox radio
| Production | England/The Netherlands, 1950 & 2022. |
|---|---|
| Bands | MW. |
| Semi- conductors | TA7642, BC337. |
| Cabinet | Wood. Size 26x24x14cm. |
| Power | Batt 1.5V (1xD) @ 1.2mA. |
| Documents | Slide deck, Schema. |
For this little garden entertainment piece, I first got myself an old speaker unit from the NVHR Swap Meet. The Plessey speaker may have been produced for several years, but I found at least one reference to it with a visible date stamp of July 1947, so it is about 75 years old. My electrical design resembles the well know Matchbox Radio (with ZN414 IC) and it's improved version, the Kid's Radio, but with some further additions. 
First, my ferrite rod antenna (from a scrapped Philips D2130) had a small extra coil, that I used to include an antenna jack (not very useful). I employed a strange type of volume control, namely a potmeter not in the signal path but in the bias resisto for the output transistor. Increasing the bias resistor decreases the volume, but also the current draw from the battery. The current draw is now around 0.6 (low volume) to 2.5mA (high volume). The D cell is good for 1 to 4 years of continuous play.
There are two LPAM stations in my region, Radio Paradijs and Jinx Radio. Both were reproduced in my garden, Jinx is even so strong that some distortion is heard, but volume can be controlled by rotating the radio. In the extremely soft weather of the Fall of 2022, I enjoyed the radio in my garden well into November.
Later, Paradise and Jinx disappeared and I listened Caroline mostly, until it was drowned in noise. Later, Paradise returned (April 2024), and I installed the volume control.
| Obtained | 6/2022 from NVHR Swap Market. |
|---|---|
| Condition | 8. |
| Value (est.) | 6,8€. |
| Sound sample | PLAY SOUND Of course, when winter is cold, I don't sit in my garden too much, but in Summer I do. Due to heavy noise in my neighborhood, Radio Paradijs is the only station I can receive well, so using my Garden set in the future depends on the continuation of this station. |
I fitted all electrical parts on a perspex sheet, which became the back of the radio. You can use the radio with headphones by simply connecting them, it will be switched on automatically then. 
For easy pickup and handling, there is an opening near the top behind which I glued a small wood bar.
The voltage on the agc capacitor varies from 1.06 to 1.00 Volts. The current into the TA7642 varies from 250 to 300µA.