I have been reading but haven't been able to wrap my brain around what to get. I would like a piece of equipment to test square waves at 1khz and 10khz for testing amplifiers for oscillation etc.
Looking for something in the $100-$200 range. I was hoping some of you may have some good suggestions. Maybe something I can order on Amazon. Sorry for the newb request. This will be my first Function generator and I feel like I am running around in circles trying to get something to produce a nice square wave to test with.
Thank you!
Looking for something in the $100-$200 range. I was hoping some of you may have some good suggestions. Maybe something I can order on Amazon. Sorry for the newb request. This will be my first Function generator and I feel like I am running around in circles trying to get something to produce a nice square wave to test with.
Thank you!
This free software has a generator, if you can use it.
https://www.roomeqwizard.com/features.html
https://www.roomeqwizard.com/features.html
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Yes, I used that with a Topping D90 and a focusrite 2i2. Both of which have too much ringing. I also tried another software tone generator.
Using the probe test port on the oscilloscope shows a clean square wave so I don't think it is the oscilloscope.
Using the probe test port on the oscilloscope shows a clean square wave so I don't think it is the oscilloscope.
DDS-based function generators are cheap and likely will do what you want : https://www.aliexpress.com/item/2255801034558731.html
I'm not sure what the risetime of the squarewave will be though - certainly better than what you'd get from a software generator but still might not be fast enough to provoke amplifier oscillation.
I'm not sure what the risetime of the squarewave will be though - certainly better than what you'd get from a software generator but still might not be fast enough to provoke amplifier oscillation.
I have an HP 3311A function generator that does pretty well. Only catch is it has a manual DC zero adjust.
I suppose the rise time doesn't have to be perfect since I can compare the signal to the output of the amplifier. I will look into that one. It is certainly cheap. However, I don't mind investing in something better with how much I will be using it for this hobby in the next few months or so.
Thanks!
If you're looking to spend more then Siglent is a reliable option in my experience. I have one of these : https://www.aliexpress.com/item/2251832429366474.html
I almost built this one - http://www.vwlowen.co.uk/arduino/AD9850-waveform-generator/AD9850-waveform-generator.htm but got a good deal on a GW Instek one so it stays incomplete (I think it was like 90% complete, the Arduino chip I bought apparently was without bootloader so a new one with a bootloader must be bought). It has a pcb mount transformer and a CLC power supply. Can picture it during the weekend.
If interested to finish it yourself, I`d give it for free, just pay your postrage to the UK. Postage`s going to be around (slightly less) than £10.
If interested to finish it yourself, I`d give it for free, just pay your postrage to the UK. Postage`s going to be around (slightly less) than £10.
A classic square is a CMOS oscillator. Schmitt-Trigger gates make it simple.
https://www.allaboutcircuits.com/technical-articles/how-to-design-schmitt-trigger-oscillators/
Nevermind the blather about top/bottom slope. Feed a second gate and those will sit hard against the rails.
Layout and bypassing must be impecable, in this or any square-ish thing (there are no true square-waves, only square-enough).
https://www.allaboutcircuits.com/technical-articles/how-to-design-schmitt-trigger-oscillators/
Nevermind the blather about top/bottom slope. Feed a second gate and those will sit hard against the rails.
Layout and bypassing must be impecable, in this or any square-ish thing (there are no true square-waves, only square-enough).
Maxim had some function generator chips, they are made by others as well.
Search for 'function generator ic', quite a common item it seems.
In the spirit of this forum, DIY it.
Square, sine and triangular waves can be generated from the same IC...
And you can combine it with a frequency counter, or make a cabinet matching your scope...be creative.
Search for 'function generator ic', quite a common item it seems.
In the spirit of this forum, DIY it.
Square, sine and triangular waves can be generated from the same IC...
And you can combine it with a frequency counter, or make a cabinet matching your scope...be creative.
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abraxalito, that is a nice generator.
mario, thank you for the offer. That is very kind. I have a lot of projects at the moment. My reasoning for looking for a simple purchase.
PRR, Naresh, both great options but I won't have any time to take on more projects than I already have lined up. I will look back into those in the future though. Very neat.
mario, thank you for the offer. That is very kind. I have a lot of projects at the moment. My reasoning for looking for a simple purchase.
PRR, Naresh, both great options but I won't have any time to take on more projects than I already have lined up. I will look back into those in the future though. Very neat.
Try locating one for sale, then, if you do not have the time to make one.
And see the output from a toy drum machine, should be enough to test an amp...
And see the output from a toy drum machine, should be enough to test an amp...
I suppose what you are saying is that it doesn't take a very good function generator to do what I am trying to do?
I use this generator, works great, not expensive.
Cost me about $150
Tenma 72-455A
Cost me about $150
Tenma 72-455A
You need to see how an audio amp responds, kid stuff compared to digital radio.
If you are around NASA, some stuff may be up for sale as surplus, even the Army and the Air Force sell old stuff, because it is no longer needed due to equipment upgrades.
The chips I mentioned above start about 25 cents....
If you are around NASA, some stuff may be up for sale as surplus, even the Army and the Air Force sell old stuff, because it is no longer needed due to equipment upgrades.
The chips I mentioned above start about 25 cents....
Okay, that makes sense. I am okay with kid stuff. Maybe I will get into the DIY side of making and fixing test equipment later on. However, if I do that now, I will never get my amplifiers built and adjusted.
I like the one Wise old Tech posted. Simple and gets the job done. I may look into that one a little bit
I like the one Wise old Tech posted. Simple and gets the job done. I may look into that one a little bit
If you really only want square waves at two spot frequencies (1 kHz and 10 kHz), a single 555 timer IC (or a newer CMOS equivalent), and ten or fifteen minutes soldering is all it takes.
To switch between the two frequencies, you can either switch the capacitor (for one ten times bigger/smaller), or switch the feedback resistor.
Need the frequency to be exact? Put a linear pot in series with the feedback resistor. Undersize the feedback resistor by 5%, make the pot 10% of the total resistance, now you have roughly +/- 5% frequency fine adjustment. Switch the cap for one ten times smaller to go from 1 kHz to 10 kHz.
And yes, you can get square waves from a 555; connect trigger and threshold together, connect a cap from that junction to ground, connect a resistor from output back to this junction. Done. (See LTSpice simulation).
Run it from a 9V flat battery, which should last you a long time.
Don't forget to put a decent-size electrolytic cap (say 10 uF) across the power and ground pins of the IC, mounted close to the chip on the PCB (protoboard will do just fine). Also plop a 100nF ceramic or film cap in parallel with the 10 uF electroytic. These aren't shown in the simulation screenshot.
Need variable output level? Use a fairly low-value pot at the output, so stray capacitance doesn't round off the waveform corners.
This is basically the even-simpler version of PRR's CMOS logic gate oscillator suggestion.
IMO, a full-blown function generator kinda seems vast overkill for the task you mentioned, unless you need a lot more features. Or just like having more capable test gear around.
-Gnouddy
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Look for 8038 based kits. They are very cheap. You get Sine, Square and triangle wave forms.
Regards.
Regards.
PRR is the actual wise one around here.
I could pick myself the username "King of the universe", but doing so wouldn't make it remotely true.
-Gnobuddy