DIY Tesla Switch Guide

[gyulasun]

Groundloop,

Thanks for the info,  I was 'blind' and did not notice the 5V AA NiMH battery label written in the same schematic I also referred to in my first answer above in this thread.

There is another issue you may be able to comment, that is the pin numbering of the SG3524 in the schematic: if you take a look at the schematic you uploaded, then the pins start from the upper left corner of the IC symbol as 1, and downwards as 2 and then comes a 9?  I cannot make it out as a 3 as it should be if it were in an increasing order. 
Pin 9 is the Compensation output and pin 3 would be the oscillator output which latter has no much sense in this circuit's case but there is sense for the compensation with the RC members tied to pin 9 as shown.
So I think the third pin under the 1st on the left side is really pin 9 and not a misprint.  Agree?

Thanks,  Gyula

[Groundloop]

@gyulasun,

Attached is a crop from my Tesla switch project. I think I have got
the correct pin outs. I think the biggest problem is to get the audio
transformers orientated the correct way. The 1K impedance must be
between the base and emitter and the 8 Ohm impedance out to the IC.

But what ways must the transformer "dots" be orientated?

Here is a link to my Tesla project (zipped file with all documentation):
http://home.no/ufoufoufoufo/
plus images of the circuit drawing and pcb.

I have not started to build this yet, need to know if I got the transformers the right
way around first.

Groundloop.

[gyulasun]

Hi Groundloop,

I agree, your IC pin outs are correctly connected.

And I think also your present connection for the transformer pins are
also correct.  Here is a data sheet for the 42TL013 center tapped audio
transformers: http://www.dspradio.org/files/42TL013-RC.pdf

It shows a phase reversal between primary-secondary and if you connect the dotted pin 4 of its secondary directly to pin 14 of the SG3524 and the signal waveform at the IC pin 14  ,say, goes positive, with respect to transformer pin 6 which is AC grounded via C8, then the transformer pin 1 on the primary side (also dotted) is correctly connected to the base of the npn switching transistor to open it with the positive pulse with respect to primary pin 3, connected to the emitter.
Regarding the other emitter output of the IC, pin 11, it also seems correctly connected but you used the undotted trafo pins, this is not a problem of course.
I believe the rule would be: if a dotted secondary trafo pin goes to IC output pins 11 or 14, then the dotted primary pin of the trafo should go to the base of the npn transistor and the same is true for the undotted secondary pin if you choose that way. 

I did not check your printed circuit board wrt the transformer connection but the schematic only.
Hopefully all the transformer pinouts are uniformly manufactured.

rgds,  Gyula

[Groundloop]

@gyulasun,

Thanks for taking time to check my circuit drawing and also for the data sheet link.
I have checked that the pcb is correct vs. the circuit drawing. So now I will order
some pcbs and parts to this project. I have designed the pcb to fit inside a Hammon 1455L1601
metal box.

Thanks,
Groundloop.

[geotron]

Concerning the 1N914 rectifier diodes, GroundLoop - I see
the one you have listed is a 200V 3A 300ns, while the specs for
the 1N914 are 100V 4A 4ns.
http://www.mouser.com/Search/ProductDetail.aspx?R=1N914virtualkey51210000virtualkey512-1N914

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I've sourced the 1000MF capacitors at a few different
stores, and have found quite a price range to choose
from. At Ralph's they've got 1000MF 50V Aluminum ones
for 1.66USD with +/-20% tolerance....
http://www.ralphselectronics.com/ProductDetails.aspx?itemnumber=SPRA-516D108M050QS6A&source=googleps

While at AllElectronics.com they've got something
by the name of '1000MFD 50V Radial' with no additional
information - http://www.allelectronics.com/make-a-store/item/1000R50/1000MFD/50V-RADIAL/1.html

Groundloop - I see that your capacitors are labeled with
the uF designation Vs. MF - are these two designations interchangeable?

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Additionally I will need a board for all of these things to
reside on, and was considering the selection over at AllElectronics.com
again. They've got a small range of different sizes to choose from,
most being about 6 x 4in -
http://www.allelectronics.com/make-a-store/category/455/Perf-Boards/1.html

Would one of these provide enough space by itself for the
Tesla Switch circuitry and Timer, or should I get a smaller
board as well for the latter?

I still haven't drawn out the timer schematic, so over the next
day or two I'll be finishing that. My work will result completely from
drawings made by hand, so as to avoid any guesswork.

Groundloop - in the original schematic from my first post, there
is a single connection from the Timer into the first series of
rectifier/transformer/transistor apparatus, while in the version
you have posted with the addition of the SG3524 this is not the
case. Forgive my ignorance, but I must ask why...