Programmable Microsecond Pulse Generator

Thread Starter

analogtv

Joined May 12, 2022
10
I'm new to the electrical side of things, but I'm looking for a pulse generator that can send pulses in increments of 100 microseconds, 600 mV, frequency range 0.01-1 Hz.

I'm assuming something like this already exists commercially, or I can make it - but any suggestions would be welcome so far I've only found pulse generators that operate for nanoseconds

Ya’akov

Joined Jan 27, 2019
5,646
Welcome to AAC.

Thew application will make a big difference to the answer. What will it be used for?

Thread Starter

analogtv

Joined May 12, 2022
10
Stimulating cell cultures

Ya’akov

Joined Jan 27, 2019
5,646
Stimulating cell cultures
How much precision do you need in timing? How much accuracy? How much repeatability?

Do you have a budget?

Reloadron

Joined Jan 15, 2015
6,581
First a little about pulses. We have a Pulse Width which I assume you want a pulse with (on time) of 100 uS. Next there is the PRT Pulse Repetition Time the reciprocal of which is the PRF Pulse Repetition Frequency. You want a PRF of 0.01 to 1.0 Hz or a PRT of 100 sec to 1.0 sec. You want a peak voltage of 600 mV. Would that be correct?

Next as Yaakov mentioned this would go much better if the application were known. For example 600 mV into what load?

Wow, I need to type faster.

Ron

MrChips

Joined Oct 2, 2009
26,076
For 100μs pulse widths you need a 10kHz clock.
Feed this into a counter chip so that you can time n x 100μs.
Next, you need a slow variable frequency clock circuit such as a 555-timer circuit in order to control the repetition rate.
Now all you need is some glue logic to finish it off.

Or you can do it with one microcontroller chip.

Thread Starter

analogtv

Joined May 12, 2022
10
How much precision do you need in timing? How much accuracy? How much repeatability?
I would need to be able to repeat the pulses in 100 microsecond timings, in terms of the accuracy ±5%.

Do you have a budget?

$1-2k Thread Starter analogtv Joined May 12, 2022 10 First a little about pulses. We have a Pulse Width which I assume you want a pulse with (on time) of 100 uS. Next there is the PRT Pulse Repetition Time the reciprocal of which is the PRF Pulse Repetition Frequency. You want a PRF of 0.01 to 1.0 Hz or a PRT of 100 sec to 1.0 sec. You want a peak voltage of 600 mV. Would that be correct? Yes a peak voltage of 600mV Next as Yaakov mentioned this would go much better if the application were known. For example 600 mV into what load? It's stimulating cell cultures. I.e. sending the pulses into a micro electrode array. Ya’akov Joined Jan 27, 2019 5,646 How much precision do you need in timing? How much accuracy? How much repeatability? I would need to be able to repeat the pulses in 100 microsecond timings, in terms of the accuracy ±5%. Do you have a budget?$1-2k
You might be best off with a high quality arbitrary waveform generator.

But, by repeatability I meant having the same setting on the instrument give the same result within some percentage.

Ya’akov

Joined Jan 27, 2019
5,646
So, since you are focused on ≤1Hz, you don't need to spend as much as you budget unless repeatability is critical. That's why I asked about it.

Thread Starter

analogtv

Joined May 12, 2022
10
Ah ok, thank you for all this. Well it does need to be repeatable. Ideally as close as possible, but I'm not sure on the cost vs repeatability curve; is 1% doable or is a ±5% fluctuation better?

I've been looking at arbitrary waveform generators, my search results may be stuck in a spiral now but I can't seem to find any relevant ones - do you happen to know any offhand that would fit the bill?

MrChips

Joined Oct 2, 2009
26,076
A budget of $1k-2k? You could probably do this for under 20 quid! Thread Starter analogtv Joined May 12, 2022 10 A budget of$1k-2k?

You could probably do this for under 20 quid!
As I say, I'm total novice to the electrical equipment side of this - typical lab equipment that you use to do this is in the $60-70k range (it does other stuff too) MrChips Joined Oct 2, 2009 26,076 With a quartz crystal oscillator you can achieve better than 0.0001% repeatability. MrChips Joined Oct 2, 2009 26,076 The next questions: the user interface. You have three controls: 1) Pulse duration 2) Repetition rate 3) Pulse voltage How you do envision controlling these? Ya’akov Joined Jan 27, 2019 5,646 As an example, the 40MHz version of this arbitrary waveform generator is under$500.00
It can be computer controlled, by LabView if you are using it. It has direct entry for all the signal parameters. It does more than you want because it's not a programmable pulse generator but those are usually for very high frequency applications and cost a lot more.

If you can deal with a lack of calibration, you can certainly build your own, using discrete components or a microcontroller. The questions of accuracy and repeatability are raised, but precision won't be a problem.

Ya’akov

Joined Jan 27, 2019
5,646
The other members are correct that you can build something very cheaply but if this is in a lab environment and that budget is not pushing anything, buying an AWG would be my advice (which I would have given to the labs that I did benchtop support for as well).

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Thread Starter

analogtv

Joined May 12, 2022
10
How you do envision controlling these?

I had envisioned a program I have written here that would trigger the pulses specifying their frequency and duration. It takes an arbitrary input I have here then returning output pulse specifications.

It can be computer controlled, by LabView if you are using it. It has direct entry for all the signal parameters. It does more than you want because it's not a programmable pulse generator but those are usually for very high frequency applications and cost a lot more.

I'm not using LabView so far, I had written my own application that creates the triggers - just nothing to connect it to at the moment; although it appears I can integrate existing code with it so will have a look; thank you.

Thread Starter

analogtv

Joined May 12, 2022
10
I may need a different thread for this, but in addition to sending pulses I also need to record what is sent back from other electrodes. There are up to 256 electrodes that send back, I'll need to build some sort of mount to hold those wires but is there an off the shelf receiver that you would recommend too?

Just wanted to say thank you though for all your help so far, very grateful!

Ya’akov

Joined Jan 27, 2019
5,646
I may need a different thread for this, but in addition to sending pulses I also need to record what is sent back from other electrodes. There are up to 256 electrodes that send back, I'll need to build some sort of mount to hold those wires but is there an off the shelf receiver that you would recommend too?

Just wanted to say thank you though for all your help so far, very grateful!
Now that is going to be a challenge. A 256 channel data recorder is going to be an expensive beast. You might be able to build something that using a multiplexer to use fewer ADCs unless timing is absolutely critical.

Look for data recorders.