Simple Keyers

After working Paul AA1LL recently, I e-mailed him to follow up on a couple of things we’d discussed in our QSO. It turns out that Paul is an afficionado of simple keyer circuits, i.e. ones that do not use a microprocessor. Without a processor, you don’t get any memory, but the circuits are very simple to build.

  • N1HFX Simple Electronic Keyer. This keyer uses just two ICs, but is not iambic. This may seem like a disadvantage, but that makes it ideal for use with a single lever paddle, such as my VibroKeyer or a homebrew sideswiper.
  • PA2OHH Simple Iambic Keyer. This iambic keyer uses two ICs and has built-in paddles made from PCB material. Each paddle is connected to a transistor circuit that is supposed to sense the change in capacitance when you touch the paddle. It should be easy enough to modify the circuit for use with conventional paddles, but you’ll have to add another IC.
  • Iambic Keyer Using 4000 Series CMOS. This circuit uses three ICs, but is more complicated than the PA2OHH. My first impression, formed by looking at the two circuits, is that the PA2OHH circuit is the way to go if you want iambic capability.

If you build one of these circuits, you might want to add a sidetone oscillator. That will add another IC to the circuit, but then you could use the keyer to send code practice. Thanks, Paul!


  1. I built the N1HFX keyer and it works really well. I have not built the other two. These circuits give you an exact 2:1 dash/dot rate but there is another class of REALLY simple keyers that use relays and have adjustable ratios. I have found and built a few of them but they suffer from having very heavy characters, i.e., the dit-to-space ratio is much greater than unity (probably due to the relay being the space determining component and no control over it). If anybody knows of a better REALLY simple circuit please pass it on, thanks. I will post my 3MEG (zipped) collection of simple keyers to as soon as is back up.

    73, Paul, AA1LL
    Mason, NH

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