Having issues with my Tesla coil
IRISHLUCK, Tue Sept 08 2015, 06:12AMSo I found these plans online and build my coil but basically nothing is happening. Just isn't working.
I have a feeling that I didn't hook something up right.
Whats a little odd is that I have a switch that is wired up to it to turn it on/off when plugged in. It has a led on the light and when flipped on the LED flicks on but then right back off.
Also I measured voltage at automobile coil and im getting mV reading.
Attached are a couple pics of the tesla coil and the diagram I found.
I can take closer pictures if needed
Re: Having issues with my Tesla coil
dexter, Tue Sept 08 2015, 07:23AM
1. check the oscillator section without the ignition coil and final stage transistors connected, you should see a square wave signal
2. check the final stage transistors
3. if all is ok but when the ignition coil is connected nothing happen either the coil is busted or the power supply is not capable to deliver the required power
4. measure the rail voltage when all is connected - if the voltage sags you'll need a higher watts transformer
dexter, Tue Sept 08 2015, 07:23AM
IRISHLUCK wrote ...
Whats a little odd is that I have a switch that is wired up to it to turn it on/off when plugged in. It has a led on the light and when flipped on the LED flicks on but then right back off.
Also I measured voltage at automobile coil and im getting mV reading.
Whats a little odd is that I have a switch that is wired up to it to turn it on/off when plugged in. It has a led on the light and when flipped on the LED flicks on but then right back off.
Also I measured voltage at automobile coil and im getting mV reading.
1. check the oscillator section without the ignition coil and final stage transistors connected, you should see a square wave signal
2. check the final stage transistors
3. if all is ok but when the ignition coil is connected nothing happen either the coil is busted or the power supply is not capable to deliver the required power
4. measure the rail voltage when all is connected - if the voltage sags you'll need a higher watts transformer
Re: Having issues with my Tesla coil
Sulaiman, Tue Sept 08 2015, 07:29AM
there are a few things that I would look at;
1) your 18V transformer looks a little small for the job,
measure the voltage across C1, 18 Vac should give about 24 Vdc
2) it is possible that one or both of your 2N3055s is dead due to over-voltage
check for collector-emitter short circuit
if failed please do not replace with more 2N3055s as their voltage rating is too low for this application
I would replace the 2N3055s with an igbt,
if you find a dead 2N3055 report back and someone here (or I) will give suggestions
3) does the spark gap 'fire'?
if yes then increase the gap until operation becomes erratic, report gap length
if no then decrease the gap until it operates, report gap length
The 555 is wired in an unusual way, especially pin1, I will have a think about it.
EDIT: dexter beat me to it!
Sulaiman, Tue Sept 08 2015, 07:29AM
there are a few things that I would look at;
1) your 18V transformer looks a little small for the job,
measure the voltage across C1, 18 Vac should give about 24 Vdc
2) it is possible that one or both of your 2N3055s is dead due to over-voltage
check for collector-emitter short circuit
if failed please do not replace with more 2N3055s as their voltage rating is too low for this application
I would replace the 2N3055s with an igbt,
if you find a dead 2N3055 report back and someone here (or I) will give suggestions
3) does the spark gap 'fire'?
if yes then increase the gap until operation becomes erratic, report gap length
if no then decrease the gap until it operates, report gap length
The 555 is wired in an unusual way, especially pin1, I will have a think about it.
EDIT: dexter beat me to it!
Re: Having issues with my Tesla coil
dexter, Tue Sept 08 2015, 09:00AM
pin 1 issue
first let assume the voltage doesn't sag
the 555 isn't referenced to ground, pin 1 is at about +8V (R1 R2 voltage divider) but the output is referenced to ground which mean it has a 8V offset which might result in a always on state of the transistors
i think the divider is used to lower the voltage across the 555 but is done wrong
either use the divider on pin 8 or use a 12-15V regulator
i'll breadboard this when i'll be back home to see how it behaves...
dexter, Tue Sept 08 2015, 09:00AM
Sulaiman wrote ...
The 555 is wired in an unusual way, especially pin1, I will have a think about it.
EDIT: dexter beat me to it!
The 555 is wired in an unusual way, especially pin1, I will have a think about it.
EDIT: dexter beat me to it!
pin 1 issue
first let assume the voltage doesn't sag
the 555 isn't referenced to ground, pin 1 is at about +8V (R1 R2 voltage divider) but the output is referenced to ground which mean it has a 8V offset which might result in a always on state of the transistors
i think the divider is used to lower the voltage across the 555 but is done wrong
either use the divider on pin 8 or use a 12-15V regulator
i'll breadboard this when i'll be back home to see how it behaves...
Re: Having issues with my Tesla coil
Sulaiman, Tue Sept 08 2015, 12:28PM
dexter, looking at it, the circuit as shown should work,
as you said, pin1 is not at 0 V,
it is also not at Vcc x 470/(470 + 1000)
due to (pin8 supply current) + (pin7 current = c50% duty Vcc via R3) + (pin3 current via R5 and Q1 + Q2 bases)
so pin1 will be at a higher than earlier calculated voltage, but it should work.
When pin3 is high there is effectively no load on it.
Why deliberately add ripple to pin1 ?, because 555 abs. max Vcc = 18V.
Sulaiman, Tue Sept 08 2015, 12:28PM
dexter, looking at it, the circuit as shown should work,
as you said, pin1 is not at 0 V,
it is also not at Vcc x 470/(470 + 1000)
due to (pin8 supply current) + (pin7 current = c50% duty Vcc via R3) + (pin3 current via R5 and Q1 + Q2 bases)
so pin1 will be at a higher than earlier calculated voltage, but it should work.
When pin3 is high there is effectively no load on it.
Why deliberately add ripple to pin1 ?, because 555 abs. max Vcc = 18V.
Re: Having issues with my Tesla coil
dexter, Tue Sept 08 2015, 03:25PM
i slapped together on a bread board the 555 side of the circuit (with the unusual pin 1 connection) used 24V supply and nothing happen on pin 3 beside a continuous logic HIGH
but if i connect pin 1 to ground the 555 starts osculating
IRISHLUCK also check pin 3 of 555 to see if its osculating
dexter, Tue Sept 08 2015, 03:25PM
i slapped together on a bread board the 555 side of the circuit (with the unusual pin 1 connection) used 24V supply and nothing happen on pin 3 beside a continuous logic HIGH
but if i connect pin 1 to ground the 555 starts osculating
IRISHLUCK also check pin 3 of 555 to see if its osculating
Re: Having issues with my Tesla coil
IRISHLUCK, Tue Sept 08 2015, 04:32PM
I will check the 555 timer as you guys have suggested. Thanks for the tips! Trying to finish this for my classmates at school.
Also the spark gap did not fire at all.
The transformer is putting out 21.1 Vac. But this is a 18Vac transformer?
IRISHLUCK, Tue Sept 08 2015, 04:32PM
I will check the 555 timer as you guys have suggested. Thanks for the tips! Trying to finish this for my classmates at school.
Also the spark gap did not fire at all.
The transformer is putting out 21.1 Vac. But this is a 18Vac transformer?
Re: Having issues with my Tesla coil
Benjamin, Tue Sept 08 2015, 10:07PM
Imho a dc flyback with a zvs driver will work nicely with a coil that size. I built one powered by a 18 volt battery and it will make very nice 6 inch sparks. Also It is important that it is rectified because when it runs at high frequency there isn't enough time to fully charge the tank capacitor before the power supply changes polarity.
Benjamin, Tue Sept 08 2015, 10:07PM
Imho a dc flyback with a zvs driver will work nicely with a coil that size. I built one powered by a 18 volt battery and it will make very nice 6 inch sparks. Also It is important that it is rectified because when it runs at high frequency there isn't enough time to fully charge the tank capacitor before the power supply changes polarity.
Re: Having issues with my Tesla coil
Sulaiman, Wed Sept 09 2015, 08:16AM
all transformers have winding resistance so when current is drawn the voltage drops,
the regulation of your transformer is
(21.1 - 18)/21.1 x 100 % = 14.7%
or more commonly
(21.1 - 18)/18 x 100 % = 17.22%
which is how I calculate it.
For a transformer of this size, that is about right.
Sulaiman, Wed Sept 09 2015, 08:16AM
all transformers have winding resistance so when current is drawn the voltage drops,
the regulation of your transformer is
(21.1 - 18)/21.1 x 100 % = 14.7%
or more commonly
(21.1 - 18)/18 x 100 % = 17.22%
which is how I calculate it.
For a transformer of this size, that is about right.
Re: Having issues with my Tesla coil
IRISHLUCK, Wed Sept 09 2015, 11:04PM
What frequency should pin 3 be?
IRISHLUCK, Wed Sept 09 2015, 11:04PM
What frequency should pin 3 be?
Re: Having issues with my Tesla coil
IRISHLUCK, Thu Sept 10 2015, 01:18AM
We just tested pin 3 and it is osculating.
Measuring at 15vpp, 2Khz, and has a 75% duty cycle
IRISHLUCK, Thu Sept 10 2015, 01:18AM
We just tested pin 3 and it is osculating.
Measuring at 15vpp, 2Khz, and has a 75% duty cycle
dexter wrote ...
i slapped together on a bread board the 555 side of the circuit (with the unusual pin 1 connection) used 24V supply and nothing happen on pin 3 beside a continuous logic HIGH
but if i connect pin 1 to ground the 555 starts osculating
IRISHLUCK also check pin 3 of 555 to see if its osculating
i slapped together on a bread board the 555 side of the circuit (with the unusual pin 1 connection) used 24V supply and nothing happen on pin 3 beside a continuous logic HIGH
but if i connect pin 1 to ground the 555 starts osculating
IRISHLUCK also check pin 3 of 555 to see if its osculating
Re: Having issues with my Tesla coil
Antonio, Mon Sept 14 2015, 02:35AM
Don't connect high-voltage circuits, as the output of the induction coil, to wood. The wood will conduct a lot and may burn, forming carbon tracks that short-circuit everything.
Antonio, Mon Sept 14 2015, 02:35AM
Don't connect high-voltage circuits, as the output of the induction coil, to wood. The wood will conduct a lot and may burn, forming carbon tracks that short-circuit everything.
Print this page