Use for the Tesla Switch

[nvisser]

Is 10mA enough to switch an opto?

Is 10mA enough to switch an opto on completely?
When looking at the datasheet of the SG3524, I noticed that the max. duty cycle when in flip flop mode is 45%. So we can say that the cigar box TS switch never ran at full 50% duty cycle.
The specs on the output section gives an Emitter output voltage of 18v when Vcc is 20V. That is about 90% of the supply voltage
So if we supply it with 12v, the pulse amplitudes must be about 10.8v.
The pickaxe chip probably only gives out 5v
I message Blackchisel on Skype the morning and we discussed the amount of current that we have to supply the opto to make sure it switch the transistors on fully
From the H11D1 the datasheet we see on the Normalized Output Current vs. LED Input Current graph that at a led current of 10mA, we already get a output collector current of 1A
At 60mA it is 2Amp!
That means to me that 10mA should be enough to switch the transistor on full, but I can be wrong

[Plazma]

Buffers/Drivers

@Visser:

Your LED current analyses look reasonable to me. As I am driving the Hd11 opto and an indicator LED in series on each of 4 driven lines, I'm using 300 ohm resistors - however, I do not drive I/O lines directly from my uChip device - I have an octal buffer between the PIC and the Tesla Switch electronics as mounted on a board separate from the computer board. The octal driver runs at the same 5V as the PIC, and makes a more cost-effective fuse than the PIC does

Now that I have recovered from a hard drive crash that wiped out a lot of my infrastructure, I hope to post detailed photos on all of what I'm doing later this week - soon as I figure out how to use my new digital camera and all of the new toys, that is . . . wheeee!!!

Nice post Visser

@blackchisel;

Thanks loads for posting the pdf on the Battery Bible - very considerate and much appreciated

Cheers,

Plazma

[ldissing]

Battery as load

@alI:

I was reading the Mueller document...again and noticed that they were using the TS to charge batteries, so I thought...I have some old dead batteries lying around that could go in there.

One was a 12V 17ah that had 3V. The other was the same, but had 4V on it.

So, I hook them up and one comes up to 10.2V and the other to 9.3V. One side of the batteries on the TS started going up quite nicely, the other going down. I switched the "load" batteries so they would be on the opposite side and the other side batteries on the TS started charging up nicely, while the other side when down. The TS batteries when up to 13.22 before I switched them out, probably should have let them to to 14.3 or so before changing the load batteries around, but here is something to say that the TS batteries WILL definitely charge, when the load is around 9 V. I would have thought it would be at a lower voltage, but it started out at 3V, so maybe 3V is the magic number and the 9V was just what was sustained in the battery while charging.

@blackchisel97

Thank you for the battery bible pdf. It was a good read.

Leroy

[Inquorate]

Inquorate, I found a schematic you posted on Dec 5th and it is not very clear for me to read(bad Picture quality) may be when I tried to down load it. In this schematic there is no connection between Opti pin 1 and 555 pin 2. Is there a newer version of your schematic?
Mark

@ mark I haven't done another schematic, I wanted to test it first, but I'll upload a (hopefully clearer) schematic as soon as I'm able. Pretty busy today.

I didn't know that the Waveform was like jb's drawing. That's cool. I thought it'd be like this one here from when I was using capacitors;

[Inquorate]

Forgot link, can't edit

YouTube - pos and neg spikes

[Inquorate]

555 timer pwm with protection from radiant spike

YouTube - 1-100% duty cycle, to 20mhz optoisolated 555 timer signal generator

1-100% duty cycle, to 20mhz optoisolated 555 timer signal generator

By popular demand, a revised schematic that won't quit

Opto 555 - Vox

Click on image for larger picture

[John_K]

YouTube - 1-100% duty cycle, to 20mhz optoisolated 555 timer signal generator

1-100% duty cycle, to 20mhz optoisolated 555 timer signal generator

By popular demand, a revised schematic that won't quit

Opto 555 - Vox

Click on image for larger picture

Hey Inq.,

Nice work mate!

I think you need to have pins 2 & 6 of the 555 joined at the hip. Something like this pic...

BTW, my PICAXE kit finally arrived today. Hopefully the optos and the diodes will arive tomorrow, please Mr. Postman!

"One small step for man...."

John K.

[Inquorate]

@ John_K thanks for pointing out the error, I deleted the last video and uploaded a new one with the connection between pin 6 and 2 of the 555

[redcar1957]

ts

Bits is this the Arduino Duemilanove ATmega328 AVR Board that you are useing?

[Bit's-n-Bytes]

Bits is this the Arduino Duemilanove ATmega328 AVR Board that you are useing?[ATTACH]4779[/ATTACH]

No, I build my own boards.

Bit's

[nvisser]

Is 10mA enough to switch an opto?

I asked this question as we want to make sure the switching transistors switch on full and we also want to use the least amount of current to do it.
I mailed Vishay Semiconductors that manufacture the 4n35 opto couplers and ask them about it. Here is his answer:
Q:How much current do I need to send through the diode part to make sure the transistor switch on full?
The opto is driving another transistor in a darlington way.
Must it be pulsed at max current of 60mA or will it switch fine at 10mA?
Regards
Naude Visser
A:
Naude, 10mA is sufficient to drive the input LED.
In fact, you may want to consider one of our photodarlington optocoupler with even lower input current.
Please consider the following;

http://www.vishay.com/docs/81865/4n32x000.pdf

http://www.vishay.com/docs/83617/il221at.pdf

http://www.vishay.com/docs/83674/83674.pdf

Kind regards,
Bob Gee
Vishay Semiconductors
Infrared Components, Inc.
Optocouplers and Solid State Relays

[John_K]

I asked this question as we want to make sure the switching transistors switch on full and we also want to use the least amount of current to do it.
I mailed Vishay Semiconductors that manufacture the 4n35 opto couplers and ask them about it. Here is his answer:
Q:How much current do I need to send through the diode part to make sure the transistor switch on full?
The opto is driving another transistor in a darlington way.
Must it be pulsed at max current of 60mA or will it switch fine at 10mA?
Regards
Naude Visser
A:
Naude, 10mA is sufficient to drive the input LED.
In fact, you may want to consider one of our photodarlington optocoupler with even lower input current.
Please consider the following;

http://www.vishay.com/docs/81865/4n32x000.pdf

http://www.vishay.com/docs/83617/il221at.pdf

http://www.vishay.com/docs/83674/83674.pdf

Kind regards,
Bob Gee
Vishay Semiconductors
Infrared Components, Inc.
Optocouplers and Solid State Relays

Hey Mr. Visser,

way to go! Thanks for the research. So, that means that you could quite easily run some optos in series whilst making sure that the transistors are all firing on all cylinders?!?! Probably still have room to run some LED's for a visual indication as well... Great news!

BTW, Mr Postman didn't deliver my optos today Hopefully tomorrow - then I can play with the digital big boys

"...and a giant leap for mankind."

John K.

P.S. JB, will call Rick in (my) the morning.

[blackchisel97]

Hey Mr. Visser,

way to go! Thanks for the research. So, that means that you could quite easily run some optos in series whilst making sure that the transistors are all firing on all cylinders?!?! Probably still have room to run some LED's for a visual indication as well..

Yes, there is no problem running LED's and optos in series. I did some tests with H11D1 and D2 and they need very little current to trigger tranny.
Thanks Vissie for your research
John K. - hopefully you'll be able to join DTS test soon
I sent you PM.
I'm hoping to get some small LABS for my TS. I'm about to give up on SLAB's. Never had much luck with them (one of the reasons for not completed COP tests in SSG Group ) neither with SC or TS. I just built another SS and will rotate them several times. Maybe this will help.


Vtech

[Bit's-n-Bytes]

I asked this question as we want to make sure the switching transistors switch on full and we also want to use the least amount of current to do it.
I mailed Vishay Semiconductors that manufacture the 4n35 opto couplers and ask them about it. Here is his answer:
Q:How much current do I need to send through the diode part to make sure the transistor switch on full?
The opto is driving another transistor in a darlington way.
Must it be pulsed at max current of 60mA or will it switch fine at 10mA?
Regards
Naude Visser
A:
Naude, 10mA is sufficient to drive the input LED.
In fact, you may want to consider one of our photodarlington optocoupler with even lower input current.
Please consider the following;

http://www.vishay.com/docs/81865/4n32x000.pdf

http://www.vishay.com/docs/83617/il221at.pdf

http://www.vishay.com/docs/83674/83674.pdf

Kind regards,
Bob Gee
Vishay Semiconductors
Infrared Components, Inc.
Optocouplers and Solid State Relays

Thanks for the research Vissie, I put some on order to try.

Bit's

[ldissing]

Transformers

I did not see any interest in the transformer version I spoke of, which is just fine, but I'd like for you all to consider what is happening in the transformer version which is quite different than the version that has optos and transistors (diode and cap to base) version.

In the opto/diode/cap/transistor version, it is all on and all off (minus cap discharge time), which is very short, but may cause something unique to happen that I have not figured out.

The transformer signaling method is unique in that there is a high initial current into the base, and it trails off as the capacitor is charged. So, the transistor is hit hard with current at a high voltage, and then gradually descends as the cap is charged up/or discharged through the opposite side. I do not know what this does to either the battery or the transistor, but you can see that this version would interject some current into the system from an outside source, i.e. a 5th battery. Is this interjection of current from a 5th battery the reason that the batteries charged in the Mueller document? Or is it the way the TS switch prefers to run, turning the transistor on hard and then trailing away? One side seems to like to charge better than the other, which may be just the batteries, or maybe a stronger potential on the cap coming from the 5th battery vs. the cap after charge. Perhaps the transformers are not perfectly matched as well.

Leroy