Mini tesla coil is not working

Thread Starter

buiquangdinh

Joined Jul 25, 2018
15
I am trying to made a mini tesla coil with d882 transistor. 0.3mm cupper wire (300 turns), 4 batterys 1.5v to make a 6v power supply, 22k resistor and a light bulb for testing. When I connect everything together, the d882 transistor become very hot, so I guess it still working. But when I put the light bulb closer to the tesla coil, nothing happen, the bulb is not light up. I try to change the secondary coil between 3 turns, 4 turns and 2 turns. Buti it still not working. I watched two videos about this, they can do that with d882 transistor and a 5-6v battery. So what is exactly problem here ?

This is my circult board.



 

AlbertHall

Joined Jun 4, 2014
11,595
Does anyone else see how this would work?
The feedback to the base of the transistor comes from the current in the secondary coil but as the far end of the coil is unconnected there can be no current and so no feedback to make it oscillate.
 

Thread Starter

buiquangdinh

Joined Jul 25, 2018
15
Does anyone else see how this would work?
The feedback to the base of the transistor comes from the current in the secondary coil but as the far end of the coil is unconnected there can be no current and so no feedback to make it oscillate.
I don't understand about the thing you said. So it's not working because I'm wrong somewhere ?
 

Thread Starter

buiquangdinh

Joined Jul 25, 2018
15
Hello,

I see the schematic is from this page:
https://hackaday.com/2014/12/22/micro-tesla-coil-makes-a-perfect-stocking-stuffer/#more-141733
There is a led in the schematic, that I can not find in your set-up.

Bertus
Oops, I forgot. I also have a led, but in my images, I put it out. I guess I don't need the led. Additionally, when I connect to the batterys, the led light up but the system still not working. I put the buib closer to the tesla coil and nothing happen.
 

Thread Starter

buiquangdinh

Joined Jul 25, 2018
15
I watched that video before. This is awesome, but it using 2n2222a. I will try to do with 2n2222a, but in this time, I still working with d882.
 

bertus

Joined Apr 5, 2008
21,669
Hello,

You are using enamel isolated wire for the big coil.
Did you remove the enamel isolation from the wire before putting it in the breadboard?

Bertus
 

MisterBill2

Joined Jan 23, 2018
9,801
The circuit, which I don't see anywhere in the posting, is an oscillator that runs at a fairly high frequency. NOTHING in the assembly in thephotos is suitable for operation at a high frequency. That is the first problem that is obvious. If the transistor gets very hot then the circuit is not oscillating, which may be caused by not having any feedback to the base of the transistor. It seems thaat the transistor is biased into conduction but that there is no feedback signal to the base of the transistor. There needs to be a current path from the base through the feedback winding and to the emitter, without that it will not oscillate. So now you know where to check.
Building anything to an on-line circuit will usually result in errors because of not having an adequate picture.of what is going on. I know that some will want to argue about that, I don't care. A circuit on paper is much better for all beginners and most other folks too.
 

noweare

Joined Jun 30, 2017
115
I think the feed back is one end of the secondary which turns off the transistor and turns on the LED. So that LED is a visual indicator that the circuit is working or not. He could try flipping the secondary coil and connecting the other end instead. The coupling from the primary to secondary is pretty sloppy in the video.
 

Aleph(0)

Joined Mar 14, 2015
597
@buiquangdinh
That's not true TC topology at all! It's just a variant of super low power Slayer oscillator! It can be vry touchy to get it running cuz feedback is just by parasitic capacitance between secondary and Gnd.

So FYI we discussed that topology on thread HERE including Ltspice simulations:)! So I say all u need is a little luck and a LOT of patience! But if you're running too low on those _virtues_ a lumped feedback cap can give instant results:cool: So plz just remember even perfectly working Slayer Osc is still vry disappointing compared to real Tesla coil:rolleyes:!
 

Thread Starter

buiquangdinh

Joined Jul 25, 2018
15
The circuit, which I don't see anywhere in the posting, is an oscillator that runs at a fairly high frequency. NOTHING in the assembly in thephotos is suitable for operation at a high frequency. That is the first problem that is obvious. If the transistor gets very hot then the circuit is not oscillating, which may be caused by not having any feedback to the base of the transistor. It seems thaat the transistor is biased into conduction but that there is no feedback signal to the base of the transistor. There needs to be a current path from the base through the feedback winding and to the emitter, without that it will not oscillate. So now you know where to check.
Building anything to an on-line circuit will usually result in errors because of not having an adequate picture.of what is going on. I know that some will want to argue about that, I don't care. A circuit on paper is much better for all beginners and most other folks too.
Thanks for your explanation, I've read some topics about how it works and I realize it need a lightly signal from lower end of secondary coil to the base of transistor then transistor will be turn off, voltage from battery is enough to turn on transistor again, time to turn off and time to turn on is not the same time because we have a 22k transistor. Therefore, this cycle will be run at high frequency. But the problem is I can't check the signal from lower end of secondary coil is exist or not. With d882 transistor, it has E C B by orders. Unfortunately, the led is not light up again @@.
 

Thread Starter

buiquangdinh

Joined Jul 25, 2018
15
@buiquangdinh
That's not true TC topology at all! It's just a variant of super low power Slayer oscillator! It can be vry touchy to get it running cuz feedback is just by parasitic capacitance between secondary and Gnd.

So FYI we discussed that topology on thread HERE including Ltspice simulations:)! So I say all u need is a little luck and a LOT of patience! But if you're running too low on those _virtues_ a lumped feedback cap can give instant results:cool: So plz just remember even perfectly working Slayer Osc is still vry disappointing compared to real Tesla coil:rolleyes:!
Oh God, I have try many times, but it's still not working .... I need some solution for it. I seen some video and they did it very simply. And I don't know why ??? I try to do with the same way at the first time, I watched a lot of videos about tutorials but something wrong, something I don't know how ?
 
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