To change the volume on the raspberry pi
amixer set PCM — -2200
will set the volume to -22db
for full power use
amixer set PCM — 0400
A 30 Kv power supply using 8 car ignition coils. The output of the coils are rectified with strings of 40 x 1n4007 diodes.
Each ignition coil, run flat out, draws around 5A at 12V so in theory the output should be around 300-350W drawing around 40A from the 12V supply.
The advantage of this drive is that there is no mains to back any fault, so it does make using the supply (slightly) safer than a mains powered unit.
The ECU (Engine Control Unit)
The heart of the power supply is the ECU. The ECU gives some control of the output power of the system. The power is controlled by a variable resistor which controls the average power to the coils.
By arranging that no coils fire at exactly the same time as any of the others, the peak current draw from the batteries is limited, this allows smaller batteries to be used at lower powers. It also smooths the output so a smaller HV smoothing capacitor may be used. It effectively gives an 8 phase rectified HV supply.
To implement this there is a PIC18f14K50 controlling the timings of the 8 coils and taking control from a variable resistor. The PIC ensures that the on time of each coil is set to a maximum value ( 2.5mS for now can be as high as 3.5mS) so the coil will not be run into total saturation. It also spreads the pulses out over the 8 coils to prevent multiple coils turning on at the same time (except approaching full power where this is unavoidable.)
<iframe src="//www.youtube.com/embed/yITbOV7NDGo" height="315" width="360" allowfullscreen="" frameborder="0"></iframe> <span style="font-family: Tahoma; color: #000000;"> <b>We have POWER!!!</b> First test at full voltage 24v (2 x 12v SLA) into a jacobs ladder. Added 0.1uF caps across each of the coils to limit voltage rise when turned off. This is a much bigger problem at 24V than 12V. No clues at actual power. Well over 10A. My meter only goes up to 10A, and the fuse blows at 12A, I need a larger ammeter, and a new fuse. <strong><a href="http://www.extremeelectronics.co.uk/blog/stand-on-tesla-coil/">Continued in Strand on Tesla Coil</a> </strong></span>
After a suggestion by Phil T at Cambridge Teslathon I tried to make a slow motion video using my EMIpi
After finding the right command line for high frame rate from https://www.raspberrypi.org/blog/new-camera-mode-released/ I tried the 90 FPS at 640/480 pixels
As I had no way to view the videos I had no idea what I’d captured. Until after the Thon.
Returning home I found a problem. First I hadnt got a .264 player, and then when I played the videos they were at normal speed.
Reading up on .264 the frame rate isn’t encoded in the video, so the player will try to play them at normal speed. A quick google revealed the answer if you use a program called GPac https://gpac.wp.mines-telecom.fr/mp4box/ you can re-encode the videos at mp4 and re-sample them at whatever viewing rate you like.
This is my test video shot at 90fps and re-sampled at 5fps (1/6 real speed see below)
and the same video re-sampled at 1fps (1/30 real speed see below)
The actual speed in these videos is open to debate.
The first one should be 18 times slower than “real” and the second 90 time slower than real. But if that were true the frames would change one a second, and that is clearly not the case.
So my guess is that MP4box is assuming that the original video was 30fps (not 90fps) so setting a frame rate in MP4box of 30fps would give an actual speed of 1/3rd real. 10fps therefore would be 1/9th real, and 1fps would be 1/30th real.
I should be able to prove this as I know the break rate of the coil, and should be able to analyse the arc progression with each bang.
Downside is obviously the resolution.
I need to try the other modes.
Although the higher resolution ones are probably not fast enough to capture anything interesting in a TC discharge.
I have been tesla coiling for over 14 years now, and I have always believed that there was no way that a tesla coil could produce more power out than was applied in. Of course there are many stories of Tesla himself creating a power system from tesla coils, but these mainly refer to his “World Power System” which was a method of distributing power, not creating it.
Recently I have been experimenting with car ignition coils to create the high voltage required for the input to a tesla coil and have had great success with this for a number of small coils.
Whilst playing with this system, I noticed a strange phenomenon. If the ignition coil was close to the primary of the tesla coil some of the large current circulating in the primary would be induced back into the ignition coil, I could even draw spark from an unpowered coil near the working tesla coil.
Thinking about this further I decided to put the ignition coil upside down into the secondary of the tesla coil and draw out the HV lead out and feed back into the spark gap and the unmodified primary coil / capacitor of the tesla coil. If I gave this circuit a high voltage pulse to start it, the tesla coil would power its-self for periods of up to a second.
After much playing, I can now get the tesla coil to run for fractions of a year with no extra input and with instantaneous outputs in the region of millions of Ergs per second.
But, this important thing is, can I extract any useful power from this arrangement?
Looking in to this I attached a common kettle and unfortunately found that the device won’t power it efficiently due to the differences in the voltages needed compared to the high voltages generated , but I have used the coil to create heat directly creating temperatures of thousands of degrees C, well in excess of the temperature required to boil water, and that could be used to power a steam turbine.
For now I will be keeping this power source’s exact details a closely guarded secret, as I would like to make millions from it, not just run my house. My prototype is happily powering my LCD clock and has been for a number of days, although I do need to clean the electrodes from time to time to maintain this level of power, so far I haven’t found a non-corrosive element better than lemon juice to keep them clean.
Next is to scale up the process.
Unfortunately I can’t get larger ignition coils, but I can get multiple tesla coils, and I’m starting to build a system with 8 coils. At present I can get about 300W at 10KV with this system, although it is being driven at 24V at present.
But to be able to draw 10KV from the machine is a great step up from only 24V. 10KV is not far from the voltage(14.4kv) used in small power transmission systems that power small industrial parks, not bad from a couple of small 12V batteries.
For more details, take a look at the V8 telsa engine http://www.extremeelectronics.co.uk/other/V8TeslaEngine/
EE and a couple of other UK tesla coilers will be providing some Tesla coil entertainment for the
The Crossness Engines Sewage Metropolis Steampunk Convivial on the 28th of September.
Details below. – Tickets from Event Brite
More details convivposter (PDF)
Come and join us for
– Electrifying Tesla Coil demonstrations in the Eastern Engine Room~
– Trader’s market
– Tea duelling
– Umbrella fencing
– Shark racing
– Costume appreciation
– Finest music from Tom Slatter
and a multitude of other eccentric escapades!:
The culmination of the great Metropolitan Board of Works’ epic civil engineering project devised and led by Sir Joseph Bazelgette. The Crossness Pumping Station is a lasting testament to the genius, craftmanship and foresight of the great Victorian engineers and notables. A gargantuan project that saved London from disease and decline, the benefits of which we still enjoy today.
Experience this magnificent 150 year old building with its 1,000 tons of cutting edge Victorian construction hailed in its day as a modern wonder of science and engineering. Decorated in the highest of Victorian design the architecture of the building is a feast for the eyes. The multi coloured wrought iron interior is both beautiful and practical.
A hidden gem in the hinterland of Erith & Thamesmead, it is rightfully described as the ‘Cathedral of the Marshes’. This is a rare chance to experience this beautifully restored Grade 1 building and grounds.
Enjoy our facilities: a lovely cafeteria, modern toilets, wheelchair access to the Visitor Centre and Engine House floor.
Ample parking with disabled spaces. Riverside walk. Wildlife Garden and a treasure trove of old engines.
Tickets from Event Brite