Basic electronics, configuration of OPAMP circuit on breadboard

Thread Starter

OPTSimon

Joined Mar 24, 2021
33
hi,
Look at this layout, check it.

All the 0V's must be connected together throughout the project
E
Hmm i though that was what i had done.

Just to clarify the 0V from the due your are refering to, that is the GND pin right?

I could rearrange the setup to look like the image you just sent - then it will also be easier to decipher what i might have done wrong since my current "setup" are abit messy?
 

Thread Starter

OPTSimon

Joined Mar 24, 2021
33
hi,
Gnd or 0V are the same in this case.
E
Hi,

I though so, then i think i need to rearrange it as your image before , since i though i had connected in a similar way - but it doesnt work.
Because i have it connected to the GND pin out on the arduino, and we had already verified that the circuit worked with the direct power suply input.
 

Ya’akov

Joined Jan 27, 2019
9,070
Simon, someone offered a solution above (sorry, I can't recall who) that might work, or be a stop gap. The idea is to use an adjustable supply to feed the 0-10V modulation input and use the Arduino to turn the supply on and off.

If it would work for you to manually adjust the modulation and programmatically time it, then it might be the easiest solution.
 

Thread Starter

OPTSimon

Joined Mar 24, 2021
33
Simon, someone offered a solution above (sorry, I can't recall who) that might work, or be a stop gap. The idea is to use an adjustable supply to feed the 0-10V modulation input and use the Arduino to turn the supply on and off.

If it would work for you to manually adjust the modulation and programmatically time it, then it might be the easiest solution.
Hmm, are you refering to keepitsimples suggestion on "page 3" ?
Because before i went with the DAC OPA idea, i though i would just trigger a relay, but the general "on/off" time would be a problem.
So i am not sure how i should do?

Since atm it would be enough for me to manually control the power input, its the ON/OFF time that is the critacal part for me, since it have to be identical for my measurements to be usefull.
 

Ya’akov

Joined Jan 27, 2019
9,070
Hmm, are you refering to keepitsimples suggestion on "page 3" ?
Because before i went with the DAC OPA idea, i though i would just trigger a relay, but the general "on/off" time would be a problem.
So i am not sure how i should do?

Since atm it would be enough for me to manually control the power input, its the ON/OFF time that is the critacal part for me, since it have to be identical for my measurements to be usefull.
I would expect you'd use a mosfet or something else solid state to manage the power and it should be sufficiently fast switching and repeatable. I don't think I would use a mechanical relay.
 

Thread Starter

OPTSimon

Joined Mar 24, 2021
33
I would expect you'd use a mosfet or something else solid state to manage the power and it should be sufficiently fast switching and repeatable. I don't think I would use a mechanical relay.
That sounds alot like the attempt i tried with a NPC transistor.
But okay, i will try to reach out to keepitsimple, to hear more about this idea :)
 

Thread Starter

OPTSimon

Joined Mar 24, 2021
33
What I gather is that you want 0-10V to be 0-100% AND you want to "GATE" the output for Various times.

What MIGHT pay out better is a 0-10V reference and a TTL pin to do the gating. The 0-100% could be computer controller or just an adjustable reference (potentiometer) or use the DAC. Just don't modulate and set the power level using just the DAC.
yes you understand correct. and the gated output i would need to trigger, where its on in forexample in 20ms and then i need to turn it off again.

Do you have an specific idea you are thinking of here with your suggestion ?

btw to everyone that have/are helping me, i am very thankfull both for the patience to explain everything, but also just that you are using some time to come with inputs/solutions. :)
 

Thread Starter

OPTSimon

Joined Mar 24, 2021
33
hi,
Look at this layout, check it.

All the 0V's must be connected together throughout the project
E
Hmm so i have tried to do it as the image that you have sent - only difference is that i did it for the A side of the OPA - i think atleast.


So those this look right ?
165257590_195587328695148_9043151061202979157_n.jpg
Red wire +12V PSU, black wire GND PSU, Purple wire GND pinout arduino due,Orange DAC input from arduino, Dark green Vout/ output and white wire, is the GND pin i use for the measurement aswell to measure Vout ?
 

ericgibbs

Joined Jan 29, 2010
18,766
hi S,
I will check it.Can I ask why are you using the Due.? in this project.

This stand alone circuit can generate 20mS pulses every 10s to 20s [ and longer if needed]
Uses two 555 Timer IC's.

Image #40 is the pulse generator, image #43 is an expanded 20mSec pulse showing the voltage amplitude as the 10k pot is stepped.
Do you follow OK.?
E
 

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Thread Starter

OPTSimon

Joined Mar 24, 2021
33
hi S,
I will check it.Can I ask why are you using the Due.? in this project.

This stand alone circuit can generate 20mS pulses every 10s to 20s [ and longer if needed]
Uses two 555 Timer IC's.

Image #40 is the pulse generator, image #43 is an expanded 20mSec pulse showing the voltage amplitude as the 10k pot is stepped.
Do you follow OK.?
E
Hi E,
Thanks - i tried to measure, at i am still measuring 0 when i turn on and off the DAC. just as before i rearrange the setup.

I am using the due since i would want to trigger this, but also another component that i already have working with an arduino setup. And i would need to trigger the two in "intervals" after each other, since this here would trigger my laser, and the other would cut the power to my sensor for it "stop" at the right time.
yes i know the second part could be done alot easier if i had the right equipment, but with the freqency counter that i currently have, i need to stop it this way to get a "proper" reading.

Okay that is perfect- since i might want to increase the pulse duration - doing my experiments for longer exposure time.
 
I was thinking of a buffered analog switch. e.g. https://www.analog.com/en/products/adg1219.html#product-overview

It might not be the most appropriate, but there is a long list: https://www.analog.com/en/products/...gle-supply-analog-switches-multiplexers.html#

One side becomes the reference and the other side ground. You have to deal with a series resistance, hence buffers.
If you actually need 0V, there is an IC that can generate a slightly negative voltage (-0.232V) . e.g,. LM7705 https://www.ti.com/lit/ds/snvs420d/snvs420d.pdf

Remember, that most OP-amps can't reach the positive or negative rails AND the inputs generally can't exceed the power supply. Analog.com does have some "op-amps" called "over the top" which can exceed.

You have to limit the input current in most OP-amps assuming the power supply is 0V or Off.

You can computer control the power level, but you have to worry about D/A noise. Manual control is possible too.

Your digital port controls the timing. CMOS inputs cannot be held floating and you would really like to ensure the output is 0 with the computer unplugged. High Z needs to be off until the ports are configured.
 
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