Syncing a camera and a pulsed flash light using a TTL signal

GopherT

Joined Nov 23, 2012
8,012
I am going to order the parts in your circuit and hopefully it will work.
However I have another simple question. In your drawing you connected the negative side of the 5 v DC supply to the function generator. Do I have to actually do this? I think it only shows that all the grounds are connected to each other? Am I right or I really need to do this? If yes, to which part of function generator should be connected?

Thanks
The Function Generator has two connections,
- ground (connecting to any ground point and the author selected the (-) of the 5v supply),
- signal (out to the BNC TEE connector)
 

EM Fields

Joined Jun 8, 2016
583
I am going to order the parts in your circuit and hopefully it will work.
However I have another simple question. In your drawing you connected the negative side of the 5 v DC supply to the function generator. Do I have to actually do this?
No. The connection to ground will be automatically provided through the shell of the BNC tee.

I think it only shows that all the grounds are connected to each other? Am I right or I really need to do this?
You're right, and you don't really need to do that.
 

Thread Starter

Biofluid Lab Biofluid Lab

Joined Feb 17, 2017
24
No. The connection to ground will be automatically provided through the shell of the BNC tee.



You're right, and you don't really need to do that.
Ok guys; I am back again. It is pathetic you have to wait a long time to receive your components and there is not a single physical store in the city I live where I can buy electronic components in person. :-(
Now that my parts are received I saw that the Op Amp is a very tiny electronic component that I cannot use on my bread-board. I am using a simple bread-board to mount all the components and so far it was good for all components except for the op amp.
This is the om amp I ordered (LT1797CS5#TRMPBF) (link: https://www.arrow.com/en/products/lt1797cs5trmpbf/linear-technology). This is very small and cannot be mounted on the board. I think it needs a special tool to install it, which I don't have.

So, please can you give me an equivalent op amp which basically does the same thing, but can be mounted on the conventional bread-board?
or ant other suggestions?

Thanks very much;
 

GopherT

Joined Nov 23, 2012
8,012
Ok guys; I am back again. It is pathetic you have to wait a long time to receive your components and there is not a single physical store in the city I live where I can buy electronic components in person. :-(
Now that my parts are received I saw that the Op Amp is a very tiny electronic component that I cannot use on my bread-board. I am using a simple bread-board to mount all the components and so far it was good for all components except for the op amp.
This is the om amp I ordered (LT1797CS5#TRMPBF) (link: https://www.arrow.com/en/products/lt1797cs5trmpbf/linear-technology). This is very small and cannot be mounted on the board. I think it needs a special tool to install it, which I don't have.

So, please can you give me an equivalent op amp which basically does the same thing, but can be mounted on the conventional bread-board?
or ant other suggestions?

Thanks very much;
An adapter for your part.
https://www.sparkfun.com/products/717
 

Thread Starter

Biofluid Lab Biofluid Lab

Joined Feb 17, 2017
24
By the way;
I also used a dual op amp that my friend had (see the attached file), but it did not work. I just left the other op amp alone, without connecting to anything else.
Actually, when I used my friend's op amp, the output signal from the delay board was kind of satisfactory in terms of delay time and voltage amplitude (in this case I did not connect the delay board to the spark generator). But, with the spark generator being connected to the board, for some reason the signal could not trigger the spark generator.
Can you tell me why?
(I did notice that the operating voltage of my friend's op amp was not within the range I want; but I gave it a try any way).
 

Attachments

GopherT

Joined Nov 23, 2012
8,012
Thanks;
Can you also comment on my other questions?
1) Can I use a normal soldering iron to mount the part on the adapter you provided?
2) Why did my friend op amp had such a result?

Best,

Your friends op amp may not reach the right voltage on the output. Many op amps can only output a voltage of 1.5 volts less than the voltage to the power supply of the op amp. You could try applying 6.5 volts to the op amp power pins and checking again it it will switch your flash.

Yes, use a decent soldering iron and it takes a special but easy technique.
1) melt some small amount of solder to one pin of the board.
2) place the chip into position on the board and hole with tweezers
3) reheat the ONE pin that had solder from step 1 with slight down pressure
4) reheat again and make sure it is perfectly positioned.
5) once you are sure the IC is positioned well, solder the other pins without reheating the first one.
 

GopherT

Joined Nov 23, 2012
8,012

EM Fields

Joined Jun 8, 2016
583
Ok guys; I am back again. It is pathetic you have to wait a long time to receive your components and there is not a single physical store in the city I live where I can buy electronic components in person. :-(
Now that my parts are received I saw that the Op Amp is a very tiny electronic component that I cannot use on my bread-board. I am using a simple bread-board to mount all the components and so far it was good for all components except for the op amp.
This is the om amp I ordered (LT1797CS5#TRMPBF) (link: https://www.arrow.com/en/products/lt1797cs5trmpbf/linear-technology). This is very small and cannot be mounted on the board. I think it needs a special tool to install it, which I don't have.

So, please can you give me an equivalent op amp which basically does the same thing, but can be mounted on the conventional bread-board?
or ant other suggestions?

Thanks very much;
At the expense of a little extra complexity, here's a circuit that has plenty of drive for the sparker, has an adjustable delay, and is made with dirt-cheap jellybean parts you can get anywhere you buy electronic parts.

I used a comparator instead of an opamp, and a delay of 25 milliseconds between the leading edge of the function generator's output and the leading edge of the pulse going to the sparker will occur when the resistance between the grounded end of the pot and the wiper is about 4200Ω.
Spark illuminator delay 3.png
 
Last edited:

Thread Starter

Biofluid Lab Biofluid Lab

Joined Feb 17, 2017
24
At the expense of a little extra complexity, here's a circuit that has plenty of drive for the sparker, has an adjustable delay, and is made with dirt-cheap jellybean parts you can get anywhere you buy electronic parts.

I used a comparator instead of an opamp, and a delay of 25 milliseconds between the leading edge of the function generator's output and the leading edge of the pulse going to the sparker will occur when the resistance between the grounded end of the pot and the wiper is about 4200Ω.
View attachment 122133
Thanks for your reply;
But I really would like to follow your previous circuit; I am already behind my schedule.
So, today I also borrowed another op amp from another friend. It is lm741 (http://www.ti.com/lit/ds/symlink/lm741.pdf).
Again, I was not sure if it would work or not but I gave it a try.
Here is a screenshot of what I got. The green line is the output of the delay circuit.
Do you have any idea if I can work with this op amp to bring the minimum voltage zero, while keeping the maximum above 4v. For example, there are offset nulls in this opamp; can I work with them to adjust the voltage to what I need.

Best,
 

Attachments

EM Fields

Joined Jun 8, 2016
583
Thanks for your reply;
But I really would like to follow your previous circuit; I am already behind my schedule.
So, today I also borrowed another op amp from another friend. It is lm741 (http://www.ti.com/lit/ds/symlink/lm741.pdf).
Again, I was not sure if it would work or not but I gave it a try.
Here is a screenshot of what I got. The green line is the output of the delay circuit.
Do you have any idea if I can work with this op amp to bring the minimum voltage zero, while keeping the maximum above 4v. For example, there are offset nulls in this opamp; can I work with them to adjust the voltage to what I need.

Best,
An LM741 just won't work.

My earliest post was based on using a single opamp to do the job, which simulated OK, but which you found objectionable because the opamp was, physically, too small for your convenience.

I then redesigned the circuit for you, using commonly available, dirt-cheap parts which you could mount on your breadboard and which simulated spectacularly.

Was that not enough?
 

Thread Starter

Biofluid Lab Biofluid Lab

Joined Feb 17, 2017
24
Thanks very much; you have been a great help so far.
I guess I am going to order the adapter GopherT has just mentioned (this one: https://www.sparkfun.com/products/717).
The reason is that I already set up my board together. Everything is mounted except for this 1797 opamp.
Hopefully I could get the result I want after connecting the op amp to my board.
I will let you know the result. But we have to wait for a couple of more days for the part to be delivered.

Best of luck
 

Thread Starter

Biofluid Lab Biofluid Lab

Joined Feb 17, 2017
24
An LM741 just won't work.

My earliest post was based on using a single opamp to do the job, which simulated OK, but which you found objectionable because the opamp was, physically, too small for your convenience.

I then redesigned the circuit for you, using commonly available, dirt-cheap parts which you could mount on your breadboard and which simulated spectacularly.

Was that not enough?
Now that I was able to get what I wanted, let me ask you about more details on the delay board and what each components do.
So what is the main component causing the delay. I assume it is the capacitor, right? As far as I know, resistors cannot make delay to the signal; they only attenuate it, right? and that's why we used op amp to bring the voltage back up, right? Is it the only function of op amp in my circuit? Just to bring the voltage back up?

Thanks
 

GopherT

Joined Nov 23, 2012
8,012
Now that I was able to get what I wanted, let me ask you about more details on the delay board and what each components do.
So what is the main component causing the delay. I assume it is the capacitor, right? As far as I know, resistors cannot make delay to the signal; they only attenuate it, right? and that's why we used op amp to bring the voltage back up, right? Is it the only function of op amp in my circuit? Just to bring the voltage back up?

Thanks
The resistor and capacitor work together to make the delay. Resistance (ohms) times capacitance (Farads) is called a "time constant". Doubling the resistance or doubling the capacitance will double tour delay. Doubling both will give you 4x the delay.
 
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