Denshi Board SR3A

The Denshi Board SR3A, also known as "SR-3A", and "SR 3A" is an educational electronics kit with 100 projects, manufactured by the DENSHI BLOCK Company of Japan in 1969. There was also a deluxe version that came with a blue coloured console panel for storing the built projects. The console made the projects more mobile and was very popular. This kit is part of the SR series with SR-1A, and SR-2A being the previous kits. In this one, you can build 100 projects because you have two denshi boards, which join for making larger projects. It has three PNP germanium transistors, consisting of one 2SA353, and two 2SB172A.

If you enjoyed building the Ladybird Book Radio, then you will like this kit as it has a large number of transistor radio circuits including a reflex radio project. There are also some amplifier projects, such as high gain amplifiers for a crystal radios, and general audio output amplifiers. There is also a lovely section on wireless transmitter circuits including a wireless record player! This is one of those times when I wish I were young again so I could spend all my time making these projects. The choice of components is good and the circuits function extremely well, which is not surprising as this is a Japanese design.

Denshi Blocks

Microphone and Morse Key

Probes

Battery Block

Wires

Cost / eBay

This is a late 70s product that was extremely popular, and consequently, majority of them would have been played with and damaged, however if you can find one that is in near mint condition, then many people would be interested in buying it. When I bought this, the box was torn and damaged, and the previous owner had not bothered to place everything back in its place. There was a tangled ball of wires and all the blocks everywhere. Batteries had leaked; wires damaged and cut, and suffice it to say it was in a right state. I managed to repair all the damage and restore it back to how it would have been when new.

This is a multi-page article, and in the following pages, you can see some of the components and the project list.

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