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Re: tesla coil does not work...



Original poster: "Qndre Qndre" <qndre_encrypt@xxxxxxxxxxx>

Hey.

Let's check your circuit step by step. Since this issue can be caused by almost anything we'll check each and every single component till we get the one which is not functional. This can be much of work but since the issue seems to be pretty hard to locate, I don't see any alternative to this method.

1. Wiring: If it's a center-tapped secondary with the center tap connected to RF-ground (NO connection to mains-ground!!), midpoint-grounded like you said, you can NOT ground one end of the secondary as well as this will short out half of your secondary winding. Do not ground any of the hot wires but only the center tap which will give you two hot wires, each having 5 kiloVolts in reference to ground being 180° out of phase, having 10 kiloVolts between both hot wires. Now connect these two hot wires to the main spark gap (with a Terry-Filter in between if you want to protect your mains transformer from the RF). Now wire primary coil and primary capacitor in series forming the LC-circuit which should then be wired in parallel to the spark gap.

2. Mains transformer: You should be able to get an arc between two pieces of wire connected to the high-voltage output if distance is close enough. If you get an arc, we're going to check the next component.

3. RF filter / NST protection / etc.: Hook up your protection circuits to your transformer but nothing else. Power it up and see if they have internal shorts etc. which will make your transformer hum or the faulty component burn. ;)

4. Spark gap: This should not be conducting unless it's firing voltage is reached. Hook the spark gap up to a low-voltage power-supply. You should not have any current flowing through it. If current flows, you have an internal shorting (electrodes touching each other) or a carbonized path somewhere. If it looks OK at low voltages, hook it up to your mains transformer together with your current-limiting. The voltage should be high enough to make it fire. If not you have to reduce the distance between the electrodes. If it fires we're going to check the next component.

5. Capacitor: If using an MMC you can try to charge every single cap using low-voltage DC and measure it's voltage to see if it holds it. Don't forget to discharge every cap after this since you have many caps in series in your MMC so you can get hazardous voltages across the whole circuit since the voltages of all the caps in series will sum up. Also remember that caps can regain charge from dielectric memory. If all the caps hold the charge properly we're going to check the next component. This measurement can be a bit harder if you have bleeder resistors across your caps.

6. Primary coil: This should be rather conductive. If it isn't, there's something wrong with it.

7. Secondary circuit: If you still don't get any output, there's something wrong with the tuning, the coupling, the secondary is broken somehow or doesn't have a good connection to RF-ground and the topload capacitor. Check your secondary circuit. If you are absolutely not sure if you manage to achieve resonance between primary and secondary circuit you can try to measure the resonant frequencies of both using a frequency generator and an oscilloscope. The coupling is usually increased until you get racing arcs, then it's decreased a bit to achieve "perfect" coupling.

Regards, Q.

----Original Message Follows----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: tesla coil does not work...
Date: Thu, 12 Jan 2006 19:35:57 -0700


Original poster: "Langer Giv'r" <transworldsnowboarding19@xxxxxxxxxxx>

its a double pole xfrm with mid point ground connected to the ground on my safety gap, and the two hot wires are connected in series with the LC ciruit, and in paralell with the main spark gap