Inexpesnive Pulse Generator - Page 1
Forum section: electronics / beginners

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 18, 2022, 05:44:04 pm
content: I am looking for an inexpensive pulse generator to do the following.I have the speed switchhttps://www.redlion.net/sites/default/files/213/3927/IFMR%20Product%20Manual.pdfit's the AC power version and the magnetic sensorhttps://www.redlion.net/sites/default/files/213/3954/LMP%20Product%20Manual.pdfThe sensor is the LMPC with open collector NPN transistor output. The sensor is going to sense the gear teeth of a gear with 56 tooth on a roller. I want to switch to switch on when the roller is turning 1 turn/sec or faster. So the frequency that I have to set for the speed switch is 56Hz. The switch can be programmed purely by pushing button, rotary sw and DIP sw. But it's easier to do it by feeding the 56Hz pulses into it. It's also good to check if it works correctly as intended.So I need a pulse generator that can generate pulses around at least 20Hz and up to 100Hz or so to set the switch and also checking the switch.Do you have in mind any inexpensive device to do this. I don't want to spend several hundres dollars for a function generator.

author: themadhippy
author_rank: Super Contributor
timestamp: May 18, 2022, 05:53:30 pm
content: 555?

author: ledtester
author_rank: Super Contributor
timestamp: May 18, 2022, 06:06:32 pm
content: First idea that comes to mind is to use a microcontroller.Aliexpress/ebay has pulse & pwm generators with a display and buttons for cheap, e.g.:http://www.icstation.com/signal-generator-square-wave-generator-channel-150khz-dual-mode-pulse-frequency-duty-cycle-adjustable-module-p-13752.html(Search for "ZK-PP1K")Both frequency and duty cycle are adjustable.Update: Here's a chart of some different versions.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 18, 2022, 08:07:37 pm
content: Thank you I ordered the PP1K.

author: BrokenYugo
author_rank: Super Contributor
timestamp: May 18, 2022, 09:43:53 pm
content: PC sound card?

author: Nothing
author_rank: Newbie
timestamp: May 19, 2022, 03:12:52 am
content: My first thought was a 555 as well. You can cut the duty cycle down to give a 5% pulse using a combination of values for R1 and R2. You can use a calculator to find the proper values to give you the pulse length you're looking for, which you can find one such calculator here:https://www.digikey.ca/en/resources/conversion-calculators/conversion-calculator-555-timerAlternately you can use a circuit simulator to make a 555 circuit and plug in different values for R1 and R2 until you get the pulse length you want, which you can find such a simulator here, it's no LTSpice but if you have access to that it might be better. This is just my personal go-to simulator for quick and dirty estimations among other things:https://lushprojects.com/circuitjs/circuitjs.htmlOR you can consult the datasheet here:https://www.ti.com/lit/ds/symlink/ne555.pdfwhich will have all of the math and formulas you need to calculate the necessary values without having to use trial and error and using nothing more than a calculator.So you've got a bunch of really good options here. Any one of which will provide you with the information you need to produce your pulse generator. Best of luck to you!

author: Capernicus
author_rank: Frequent Contributor
timestamp: May 19, 2022, 08:09:53 am
content: hook up a capacitor to ac, and ull get ac pulses, at the strength of the capacitance + at the hz of the ac wave.

author: Gyro
author_rank: Super Contributor
timestamp: May 19, 2022, 09:15:33 am
content: Quote from: Capernicus on May 19, 2022, 08:09:53 amNo you won't. Assuming that you're talking about and AC sine wave, then you will get a smaller sine wave with a phase relationship depending on the size of the capacitor and load resistance.If you're talking about AC mains then don't encourage others to follow your own very dubious path.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 19, 2022, 09:31:42 am
content: Thank you everyone. I didn't want a hom built unit. I already order PP1K for less than $15 from Amazon.