Denshi Block ST-45

The ST-45 is an educational electronics kit manufactured in Japan by the Denshi Block Company in 1971. It has enough Denshi Blocks to make 45 circuits utilising silicon transistors, and an 80-page manual documents all the circuits nicely. If you are not familiar with the ST series, then this one is a good place to start. There were five in the series, ST-25, ST-45, ST-100, ST-125, and ST-155. This electronics lab is a step above the ST-25 and comes with an amplifier module. The module consists of a Class A amplifier circuit, which drives a loudspeaker. It also has a volume control and battery compartment inside it. There is also an ST-100, which is a step above this kit, and allows 100 project circuits. In this series, the Denshi Blocks are transparent, and the main chassis to hold these blocks is a plastic container with a transparent lid. The container also has a handle so that you can carry your project around.

The UK distributor for the Denshi Block Mfg. Co. Ltd was the Electroni-Kit Company based in London.

This kit is ideal if you are interested in making crystal radios, and simple one transistor, and three transistor radio circuits. Usually kits this old use germanium transistors, however, this one uses silicon transistors. One of the transistors is a 2SC372, which is a high-frequency amplifier with a maximum hFE of 400.

There is also a wireless microphone circuit, which shows how to make an AM transmitter. The performance of this circuit was very good.

Cost / eBay

Very few of these kits would have survived from 1971, and those that makes it, are usually in a poor condition. However, the fun is sometimes in restoring them to their former glory. If on the rare occasion, you find one of these in mint condition, sell it on eBay. There are many collectors willing to pay top dollar for something like this.

Some issues to look out for is battery leakage from old batteries that have been left in the box for decades. Sometimes the manual is missing, and even missing blocks, which are difficult to replace.

You can see more of this kit in the following pages of this multi-page article.

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