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Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Hi guys, I started experimenting with feedback using my single switch and the Red Traffic Cone beast and first attempts are not bad. Sparks are 70cm long (no interrupter!). Unfortunately my feedback had very strange behavior and I will need some help to figure it out. I’m using Steve's mini sstc design with following modifications: There is no external oscillator (like 555timer) and the system is powered from a 12V battery. The funny thing is that my body is a necessary part of the feedback system (more on the video). I have to touch the antenna to start oscilations and keep the system working. Moreover my body needs to be in certain position, I have to be sitting at certain distance from the coil (not very practical). However, the results are quite impressive so now I need to solve the problem how to avoid my body to be part of the system. Any suggestions?
Video: It is not the full power; I used only 150V at maximum!
And few pictures
Plying with higher voltages was deadly for one of my IGBT. This spark-over killed it .The spark hit the driver not the primary! I will have to cover the secondary with few layers of epoxy to avoid this in the future.
wow, awesome result, so this coil is running on CW? i had almost similar problem with this antena, try to use a 1N4148 diodes instead of 1N60 or dircet antena to the top, or make it longer, or try it aim to the secondary.
Registered Member #1623
Joined: Tue Aug 05 2008, 03:31PM
Location: The Netherlands
Posts: 39
Very cool result Mates. Have you tried to add a capacitor from your antenna to ground? Your body is basically a capacitor and probably grounded one way or the other, only i have no clue what ratings, also there are very few datasheets for this type of cap.
Registered Member #1025
Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566
Hi coilers, New update…
I finished current transformer feedback and tried the full power for the first time. The coil works pretty well. I plan to prepare complete schematics of this concept including the power part and the driver. I'll post it soon.
Registered Member #2161
Joined: Fri Jun 05 2009, 03:36PM
Location:
Posts: 247
Indeed, very good results! Must say I am in love with the conical secondary, it really sets the whole coil apart from the pack.
I would also like to state that I applaud your continuing efforts with the single switch topology you have been working around with for quite a while. It is really paying off! Congrats on a great coil.
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My single switch with feedback - 70cm sparks!
