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CD4046 datasheet, R1 and R2 and C1 that determine frequency range of this IC.

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tarakan2

Mon Aug 29 2016, 07:22PM

Registered Member #3859 Joined: Sun May 01 2011, 03:47PM
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Posts: 179

On the datesheet of CD4046 there are graphs on page 4 and 5.
http://pdf1.alldatasheet.com/datasheet-pdf/view/26873/TI/CD4046.html

Those graphs show what center frequency, minimal frequency and maximum frequency can be obtained with different values of C1, R1, R2.
MEDIUM

I am building this circuit.
And with the tables on the datasheet for CD4046 I am getting center frequency of a little bit less than 6MHz.

In the original circuit, R1= 12K, R2 = 16K , C1= 330pF = 0.00033uF . This corresponds to 10^6 Hz on the graphs provided. Tesla coils as big as mine cannot work at such high frequency.

I have a Tesla coil secondary that is a little different than the one that the author used for his circuit. I would like to use this Secondary.
For this reason I would like to play around with the values of the R1 , R2 and C1 to make sure that this circuit produces the resonant frequency of my secondary.

The resonant frequency of my secondary:
490 turns of 0.32mm wire on a 4inch PVC pipe.
The resonant frequency is about 852 KHz but my calculations may be wrong.

How big does the current in the primary circuit need to be? How thick should the wires be in the primary side of this circuit?

Would attaching a thick primary coil, made out of a telephone cable with all strands tied together in parallel make sense if I am using 0.68uF capacitors with leads that are only 0.6mm in diameter?

Should I redesign my circuit to use banks of smaller capacitors instead, to make the total diameter of the leads greater?

Thank you!

Antonio

Tue Aug 30 2016, 11:53PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

I see something as 200 kHz, or 2 x 10^5 Hz.

tarakan2

Fri Sept 02 2016, 05:53AM

Registered Member #3859 Joined: Sun May 01 2011, 03:47PM
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Antonio wrote ...

I see something as 200 kHz, or 2 x 10^5 Hz.

Capacitor is 3.3 * 10^(-4)
R1,R2 are in the range of 10KOhm.

I get MHz range according to the table.

Uspring

Fri Sept 02 2016, 10:07AM

Registered Member #3988 Joined: Thu Jul 07 2011, 03:25PM
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Posts: 711

I agree with Antonio. The link you provided doesn't seem to work for me. I used

How big does the current in the primary circuit need to be? How thick should the wires be in the primary side of this circuit?

Max primary current depends the choice of primary inductance. You don't want to exceed the capabilities of the FETs.

tarakan2

Fri Sept 02 2016, 09:16PM

Registered Member #3859 Joined: Sun May 01 2011, 03:47PM
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I can replace TI CD4046BE with a HEF4046B by NXP?

They are not exaclty the same thing.
I have the TI but I may buy HEF4046B so it matches a more modern datasheet and your experience.

I need to obtain some frequency that matches my Tesla Coil secondary that I bought:

The resonant frequency of my secondary:
490 turns of 0.32mm wire on a 4inch PVC pipe.

How do I design the primary? Does it need to be thick? (Conductors on the circuit board that lead to the primary are not very thick. Capacitor leads are less than 1mm)
Thank you.

Uspring

Mon Sept 05 2016, 09:47AM

Registered Member #3988 Joined: Thu Jul 07 2011, 03:25PM
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I believe you can also use the TI chip. They seem to be similar in terms of the frequency diagrams.

Steve Conners web pages seem to be under construction. I'd use the same primary inductance he did (which I don't know), scaled by the frequency. If you, e.g., want to use the double frequency that he used, then you should halve the inductance.

I dont think. 1mm leads of the caps matter much if you keep them short. Your primary copper wires should be at least 4 or 5 mm in diameter. Use JavaTC to calculate secondary res frequency or better measure it. For the design of the primary also use JavaTC. It will also tell you the effective copper resistance of the primary in cluding skinn effects. From there, with the max current of the primary, you can get an estimate of the power dissipation in it, which will help you to choose a thickness.

tarakan2

Wed Sept 07 2016, 01:07AM

Registered Member #3859 Joined: Sun May 01 2011, 03:47PM
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Thank you.
I believe that all the Tesla magic that puzzles historians of science was in his (now obsolete) PLL circuitry. He built powerful systems that were capable of changing their frequency to tune into other sources of frequency.

I want to build PLL Tesla Coil circuits to test some of the greatest myths surrounding Tesla physics, in scale.

My CD4046 is different from the one you referred me to. My IC uses DIFFERENT C1, R1, R2 to achieve a desired frequency. I thought of buying a different IC but decided against it.

tarakan2

Fri Sept 16 2016, 02:49AM

Registered Member #3859 Joined: Sun May 01 2011, 03:47PM
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Working on the circuit with the existing IC that is a TI version of CD4046. I want to replace 12K and 16K resistors with 100K potentiates connected in series with 5K resistors for safety.
I would also like to use a variable capacitor. instead of 330pF.

Do I need to make the primary work in resonance with the secondary? Which part is easier to make adjustable? Do I need to make a primary coil so I can change the amount of engaged coils on it?

Should I use the same capacitors - 2 X 0.68 uF ?

Thank you.

Uspring

Tue Sept 20 2016, 10:39AM

Registered Member #3988 Joined: Thu Jul 07 2011, 03:25PM
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Do I need to make the primary work in resonance with the secondary?

No, the primary isn't a resonant tank in a SSTC.

Which part is easier to make adjustable? Do I need to make a primary coil so I can change the amount of engaged coils on it?

An adjustable primary would be nice, so you can adjust the load to the bridge.

tarakan2

Mon Oct 03 2016, 03:28AM

Registered Member #3859 Joined: Sun May 01 2011, 03:47PM
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I bought the secondary and I may wind several identical secondaries for an experiment.

Making a primary is more difficult for me.

I assume that one 0.68 uF has opposing charges on its sides, while the other is always shorted by a closed MOSFET when this circuit is in operation.

I need to measure or calculate the LC of the primary using this data. Would a multi-strand telephone cable make a good primary? I want to tie all the strands together at the ends and use it.

I need the generator to work in the range of frequencies that the primary LC falls in and the secondary as well?
Secondary coil will always drift around. This is the whole point of PLL as I understand.

Double pendulum -- Is Tesla Coil an electric analog of this mechanical system?

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