Yet Another AtTiny85 Keyer

After a renewed discussion on the SOTA Reflector about using a Quansheng UV-K5 handheld for CW, I built yet another AtTiny85 keyer, by just using the chip, and not replicating the DigiSpark layout.
(see my Digispark keyer in a previous post here).

Leaving out all unneeded components made it a lot smaller and lighter, this is the (very) simple circuit.

I built this circuit on a piece of perfboard, it measures only 70 x 12 x 9 mm.

If built with SMD components, it would even be much smaller, maybe it can then be built inside a paddle ?

I found a small plastic box that used to contain some O-rings from the DIY shop, and it fits the keyer nicely, powering it from a 650 mAh Li-Ion cell from a cordless phone.

Total weight , including the cable, but not the paddle, is only 48 gram.

Now, instead of building a keyer into a paddle ... I had another idea : buid the paddle inside the keyer !

I found two very small pushbuttons from old 3.5" floppy disk drives (the write-protect switches).

I glued two of those in the corner of the plastic enclosure of my keyer, and connected them in parallel to the paddle input connector.

And while I was at it, I also added a 4-pin header to the battery, to connect a Chinese charging board. Inserting the pins the wrong way does no harm, nothing happens, since only two of the pins are connected.

For the Quansheng, I built two adapter cables, one with the cut-off 2.5mm connector, to listen to the receiver on speaker. The other cable has both the 3.5mm and the 2.5mm connector, and is meant to be used with headphones.

Both cables have a pushbutton that serves as a straight key. 

Total weight of the keyer with the small adapter cable is 59 gram, with the larger adapter it's 80 gram.

I posted a short video of the keyer on my YouTube channel.

If you have questions about this project, feel free to mail me at my QRZ.com address.

Happy tinkering !

73,

Luc ON7DQ