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If you've no spark at your spark gap, you've got yet another problem. I'm assuming (perhaps incorrectly) that you have your primary circuit connected up properly, and that you've not set your spark gap so wide that your transformer voltage is insufficient to jump the gap.
Just because you hear your NST humming doesn't mean that it's generating any output voltage (or adequate output voltage).
So, first thing is to make sure that your transformer is still alive. Disconnect your primary wiring from the transformer's HV bushings, and connect a small, stiff piece of wire (like a straightened paper clip, a piece of solid copper wire, etc) to each HV bushing, and form each wire so the free end is about 3/8" from the transformer's metal case. Power up the NST for a few seconds, and make sure that you get a healthy, continuous arc from EACH wire to the NST case.
Perform this test, and if you get a healthy arc from each bushing, then your transformer's OK.
Reconnect each of your primary circuit's wires to the transformer's bushings, and carefully trace your wiring from one bushing through the entire primary circuit, looking for a either a short circuit, or an open circuit.
If your transformer's OK, but you get no activity at your main spark gap, then either you've got your gap set WAY too wide, or you have something connected up incorrectly in your primary circuit.
Close your safety gaps down to 3/8", and power up again. If you don't get continuous arcing at the safety gaps, then you've somehow shorted your NST by some error in your Terry filter or your primary circuit.
Herr Zapp
So being that the gap may be set to wide. (Since I haven't narrowed out the NST yet)
What would I set it to since its set to .07 right now? Should I try .05? (If the NST is working alright that is, and is not blown)
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
IR -
Please just try to follow the suggestions, in sequence.
If you have adjusted your spark gap electrodes so there is ~.50" TOTAL gap width (sum of the 7 individual gap segments), then your NST (if it's still alive) should have no problem arcing across the electrodes.
TEST YOUR NST FIRST, as suggested. If you are getting zero sparking at either your main spark gap or at the safety gaps, then something is very wrong.
Do the quick test with a paper clip from each NST bushing, and make sure that each bushing generates a good 3/8" - 1/2" arc to the NST case. This will confirm that your NST is alive.
Then, disconnect your new spark gap from the primary circuit, and connect it DIRECTLY across your NST bushings. If you don't get continuous arcing across all the gap segments, then either the gaps are set too wide, or the entire gap is somehow shorted.
Looking at the one photo of your MMC, I see what appears to be TWO copper terminals at one end of the board. Why are there two terminals at one end?? Have you laid out your MMC in a "U" shape, with your maximum voltage terminals right next to each other, rather than at opposite ends of the layout, as far from each other as possible??
Also, are your bleeder resistors 1/4 watt, or 1/2 watt?
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
IR -
The NST and NST/spark gap tests previously suggested wouldn't be affected by any local climatic conditions; the coil itself won't be "running", just the NST will be powered.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
IR -
You wrote: "After I test my NST, I can just take the ends of the NST and connect them straight up to the gap to see how it works correct?
From my 8-3 suggestions for you:
"Then, disconnect your new spark gap from the primary circuit, and connect it DIRECTLY across your NST bushings. If you don't get continuous arcing across all the gap segments, then either the gaps are set too wide, or the entire gap is somehow shorted."
I'm not sure how to explain this any more clearly ...... and of course for this testing, yoiu don't need your RF ground rod because you are not actually running your Tesla coil, you're just testing the NST and spark gap, isolated from the rest of the coil.
DO THIS: REMOVE YOUR NST FROM YOUR TC. Set it on any surface. Place a piece of wire on each bushing. Bring the ends of the wires near the casing of the NST. PLUG IN THE NST. Use a piece of wood to position the wires if they are not arcing to the case. If you get closer than 1/4" and still no arcing from either side.... SOMETHING IS WRONG WITH THE NST.
Well to test the NST I still have to ground it dont i? I mean there is a ground on it. And how I have it set up, is that the ground of the NST will have to connect to the grounding rod. I dont have another way from how its wired.
You do have to ground the NST, but you don't need a ground rod for that, the NST can be grounded right to your wall socket's ground connection. There is no HF/RF from a NST.
What do you mean by shorten the spark gap out? Do you mean "how do you reduce the overall gap?"?. If that is what you mean, then the fact you are asking it means there is a good chance you did not design/build your spark gap properly, and that means it -could- be a major source of problems. In a "copper tube" multi segment gap you simply use less segments to shorten the gap. Keep in mind that if the tubes are not perfectly parallel, they will not arc across their entire surface, and the gap will not function correctly.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
IR -
For this 30 second test of the NST and spark gap, just connect a 3-wire AC line cord to the 2 AC input terminals on the NST, and connect the cord's green wire (ground) to the ground terminal on the NST case.
It sounds like you are confused about what we are trying to do here, so lets simplify it as much as possible:
1. Physically remove the NST and your multi-segment spark gap from the Tesla coil. 2. Connect an AC line core to the NST AC input & ground terminals. 3. Connect a short (~3") piece of bare, solid wire (can be anything, even a pair of paper clips) to each NST HV output bushing, and carefully bend/form each wire so the free end is about 3/8" - 1/2" from the NST's metal case. 4. Plug the NST in, and verify that there is a continuous arc from the end of each wire to the NST case. If you get a continuous arc from each wire to the NST case, then your NST is likely OK. 5. Unplug the NST, remove the short wires from the HV bushings, and connect your spark gap directly across the NST bushings using appropriate lengths of insulated wire. 6. Plug the NST in again, and verify that you get a continuous arc between all the gap segments. If you don't get a continuous arc, either your total gap width is too great, or your gap is somehow shorted. 7. If your gap width is too great, remove one of the HV wires from the bolt on the last copper pipe, and reconnect it to the bolt on an adjacent copper pipe. This "deletes" one of the gap segments from the circuit, and reduces the total width. Repeat steps 5 and 6 until you get continuous arcing across your spark gap. Then, when you replace the spark gap in the Tesla coil, use the number of gaps that gave you continuous arcing during the test.
Also, I don't think you ever answered the question about the wattage of the bleeder resistors you used in your MMC: 1/4 watt, or 1/2 watt? Do you know the difference between a 1/4W and 1/2W resistor? And are you 100% sure that the individual resistor values are at least 10 meg ohms? (that's 10 MILLION ohms for EACH resistor). Do you know how to read a resistor's coor code, or do you have a multimeter with a resistance range that you could use to measure each resistor?
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First time Tesla builder, Terry Filter caps popping?
