Short circuit: A Morse Code Practice Oscillator

Maybe not state-of-the-art technology but Wally Sawyer G7FHN offers a quick and easy project for a Morse code practice oscillator. Perhaps this could be a Christmas project and entertain and inform family and friends as suggested in this month’s What Next Column.

As featured in January 2018, Practical Wireless
Author:
Wally Sawyer

Maybe not state-of-the-art technology but Wally Sawyer G7FHN offers a quick and easy project for a Morse code practice oscillator. Perhaps this could be a Christmas project and entertain and inform family and friends as suggested in this month’s What Next Column.

The author spent nearly 30 years teaching Sea Cadet Radio Operators radio procedures, including Morse. There were a number of books for the cadets to fill in as they learned their subject. These task books covered the three classes, RO3, the lowest level, through to RO1.

The RO3 book contained details of a simple Morse oscillator, the details of which appear here. I must acknowledge the layout designs by Mike GW7EUL.

As can be seen, the circuit, Fig. 1, uses a 555 timer chip. The output is not exactly a sinewave but the results in a pair of headphones are reasonable and construction is straightforward.

The next three figures, Figs. 2 through 4, show the Veroboard layout, track cuts and suggested mechanical assembly. Table 1 has the components list. Of course, you could equally use other methods of assembly, including Manhattan-style as often recommended by George Dobbs G3RJV when he wrote for this magazine.

I don’t know how many were ever built but this is offered to readers who fancy a simple project or perhaps part of an amateur Intermediate licence course.

As far as getting hold of a Morse key is concerned, you could try fabricating your own. Over the years, people have made Morse keys from clothes pegs, spoons and other hardware found around the home. Google “homemade Morse key” for example, and you will find lots of suggestions and some YouTube videos. Or you could look on eBay – a quick search showed new ones from around £20 and a number of second-hand ones available for significantly less.

Most of all have fun with your Morse practice, the traditional way!

Table 1: Component List

R1     56?
R2     1k?
R3     10k?
RV1    1k?
RV2    100k?
C1    10nF
C2    22nF
IC1    555
Strip Board
Box
Jack socket (x2)
Jack plug (x2)
Battery connector

Fig. 1: Morse oscillator circuit diagram.
Fig. 2: Board layout.
Fig. 3: Track side of Veroboard.
Fig. 4: Suggested assembly.