Build a beeper mousetrap (2)

A cheap light portable iambic paddle, "ugly homebrewed" style, from AC4RD

I started operating portable from my back yard two years ago, andn had a lot of fun doing it.  Then recently I got an FT-817 (hi, K4WGE!) and started doing QRP CW from the yard.  It's a HOOT to work Europe or the Pacific on 2.5 or 5 watts while sitting in my back yard.  :-)
full view of mousetrap on radio
One minor annoyance was that my regular CW paddles weigh almost as much as the radio; it wsn't very convenient to carry those out every time I wanted to play with the radio outside.   I homebrewed a sideswiper but didn't much like it.  I bought a cheap old sideswiper (a Vibroplex imitator with a light plastic base) but discovered I really prefer iambic paddles--I just couldn't get used to the single-arm style.

So I started toying with the idea of building iambic paddles--I wanted them to be cheap, light, sturdy, and effective.   ("Sturdy" is still an open question, but we'll get to that.)  I wound up putting together a set of paddles with a mousetrap, a wine cork, and some brass strips from the hardware store.  The first set worked pretty well, but there was no real way to adjust the gaps' spacing or tension.

This is the "Build a Beeper Mousetrap Mark II.b" model--an improved version of the original.  A simple U-shaped piece of the brass strip is tapped for #6 brass round-head bolts, which  provides a spacing adjustment.  The tension can be adjusted by adding a piece of light foam between the contact arms--the amount, location, and type of foam provide adjustment variability.  But I have not added the foam on this one; the tension is just about right for my taste.

overhead viewI won't provide many details about construction--it's entirely improvised anyway, and the photos show it well enough.  (If you're the type who thinks this might be fun to try, you're certainly capable of coming up with your own design.)   :-)  (And the photos are bigger than they web display, so you can zoom in to see them better if you want.)

The mousetrap has the spring disconnected and the trigger removed.  The big trap arm is bent back on itself to provide a mounting bracket for the wine cork (synthetic works better than real cork.)   The arms are brass strip ($1 at the hardware store); the hardware is #6 brass, the fingerpieces (and the plastic on the contact arms where the gap screws touch) are cut from guitar picks.  "Gorilla glue"' holds things down where they need to be held. :-)

Do they work?  Yes, they actually work pretty well.  The feel isn't quite as good as my real paddles, but I use them routinely (I've actually got them stuck to the top of my 817 with some silicone sealant.)   And these paddles cost less than $4 even if you buy most of the parts new, so even if they fall apart or get broken, it's not a big deal.  I can make a set in 2-3 hours using no tools but a crescent wrench (for bending the brass and tapping the holes) and a Swiss Army knife.  :-)
side view