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Portable Low Frequency square wave generator circuit - Solved - page 3
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Zero999:
This might not matter. If all the circuit at the other end is doing is looking for rising/falling edges above and below 0V, then the low frequency part of the signal is unimportant.
Laszlo:

--- Quote from: Simon on May 28, 2019, 12:05:54 pm ---If I leave them blank I get the same strange result as you at 1V and 12V, but if I set the square's rise and fall times to a realistic 150ns I get the expected pulse height and shape at the 22k.

--- End quote ---

The rise time is around 120ms with no load attached.


--- Quote from: Zero999 on May 28, 2019, 02:50:02 pm ---This might not matter. If all the circuit at the other end is doing is looking for rising/falling edges above and below 0V, then the low-frequency part of the signal is unimportant.

--- End quote ---

Unfortunately, I do not have the schematics of the rig so what you guys are saying must be true.

Did some other tests on it, obviously confirmed what you guys were pointing out that the series capacitor will block most of the square wave out. At least I have learned something new again. Attached a picture with the capacitor in series with the load. The yellow trace is measured at the output of the 555 timer, blue is measured at the load.

Regardless, the circuit does work in the field and I even managed to squeeze it in a box. So thanks again for the help.
Simon:
If you want a stiff 12Vpp square drive the easiest way is to use a micro or the 555 to drive a TLE5206-2 (2 channels). Run it off 12V and have a stiff enough virtual ground at 6V
Zero999:

--- Quote from: Simon on May 28, 2019, 05:28:44 pm ---If you want a stiff 12Vpp square drive the easiest way is to use a micro or the 555 to drive a TLE5206-2 (2 channels). Run it off 12V and have a stiff enough virtual ground at 6V

--- End quote ---
Why would you need an MCU as well as the 555 and TLE5206-2? The MCU and TLE5206-2 is all that's needed.

Beware, there will probably come a point in future when you can't get the TLE5206-2. Mouser says it's obsolete and Infineon says "not for new design", in the product status section.
https://www.mouser.co.uk/ProductDetail/Infineon-Technologies/TLE5206-2?qs=rY7msk5yxfZPdjTP77cv7Q==
https://www.infineon.com/cms/en/product/power/motor-control-ics/intelligent-motor-control-ics/integrated-full-bridge-driver/tle5206-2g/
Simon:
I said 555 or mcu.
I asked infineon about the TLE5206 and they said that it would only be phased out if demand drops and yet there is no direct replacement. I think the version with lead is obsolete. For a one off I don't see a problem anyway. I use it as a protected output driver as it is short circuit and over temperature protected.
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