Maggot – Classic Table top Magnifier Tesla coil


After The Nottingham Tesla Workshop, I started thinking about Tesla Magnifiers. Again not having ,much space I thought I'd have a go at making a table top magnifier. I'd picked up a LOPT and with the experience I'd got from making IkleTess How hard could it be...

See below for the sequence of construction..

Current Configuration.

Power from an OBIT 10kv @20Ma
Primary 10T 2mm speaker cable with 3x2.2nF caps in parallel (6.6nF). Spark gap , Small Rotary.
Secondary 80mm tall of 0.25mm wire 300 turns. wound on a
 kitchen roll former(30mm diameter), then epoxy potted to 10mm all round. (primary wound around potting), top of coil extended 40mm and potted 5mm thick, end of coil capped with toroid made from 4mm copper tube. (pool made when a "cell" leaked during potting")
Tertiary Coil 1200T over 150mm of 0.125mm wire on kitchen roll former, bottom terminated in 4mm copper tube toroid, topload air freshener taped with aluminium tape 70mm diameter 25mm thick.
Total Size 260mm tall (10")
Output Depending on configuration 4-5" arcs, 3" streamers.(at 24V in)

ToDo I need to play more with tuning, and especially spark gaps, maybe another small rotary or a magnetically quenched static..

Primary 1, A test really, As you can see it was rather crudely constructed. The insulation between the primary and the secondary was 4 sheets of OHP plastic. Clearly not enough. I tried more but it was obvious that I needed much more insulation.
Primary 2, Rather better built than P1, more OHP , about 8 layers. and about 20mm gaps from primary to secondary.
P2 also lit up like a christmas tree in operation.

So P3, I potted the primary in epoxy resin, It arced over the top!

P3a, I extended to top 40mm and potted the tube with 5mm of epoxy resin. It actually arced through the potting and the plastic outer I'd used, but much weaker arcs.

P3b (photo), I scrapped the full height primary winding and re-wound the primary with 2mm insulated speaker wire around the bottom only, much better, almost no arcing, the end of the primary still arcs to the white plastic top, but not much. I can live with it and its a good indicator of tuning.

After the success of the small rotary I built for ikletess, I built another one.

The construction is as before, but with a much better engineered motor, (rs380 from memory). The construction is from 2mm acrylic (again) and it has 5 stationary and 4 rotating electrodes. This means that at each rotation of the motor there are 20 passes of an electrode. So at around 20 turns/sec I get 400BPS.

This time I used brass nuts and bolts, they are surviving much better then the steel ones I used in ilketess even with the greater power throughput.

Found a 10kv 20mA OBIT ( also blew one of my lopts), so I decided to use it to power Maggot.
Much better than a LOPT. Shame I can't run it from a battery, (yet).

Nice 4-5" arcs, loads of power, still a bit of arcing from the primary, but good overall results.
I need to build the while lot into a better framework, and then do some tuning.

Also now I have more power available, I think a bigger top load is in order.

Ok so winner of the wierd top load of the month!!

Its a plastic egg shaped "thing" I found in a flower shop. 3" in diameter and 5" long. I've no idea what it would have held, but it comes in two peices.
I have of course wrapped it in Aluminum foil.
The best thins is, sparks only come out of one end (ok, so a few sparks from the back) so you can direct the discharges.
This now takes the primary cap up to 6.6nF.

6"-7" Sparks.....

Amazing what a bit of tuning can do..
8" sparks to air, haven't tried to earth yet.
Also It appears to have bouts of 12" Sparks, but I cant find out what makes this happen. It dosen't do it all the time.
More experementation needed.

Decided it was a bit scary to use a mains plug to turn it on and off so a mini controller was born.
Also added rotary speed control in, but couldn't fit either a power supply or battery into the control box
(Battery's are safer anyway 🙂 )