Electronics > Beginners

Portable Low Frequency square wave generator circuit - Solved - page 3

<< < (13/16) > >>

Simon:
and 1KHz

Laszlo:
I'll try it in a minute. I have tried simulating the circuit in multisim but it was not having it at all. There was no output from the 555 timer.
So you think that the series rc is not necessary?

There is one question I also could not make my head around it. When I put a diode in series with the output, it distorts the signal to nothing. I've tried multiple diodes and it's virtually the same.

Sent from my S60 using Tapatalk

StillTrying:

--- Quote from: Laszlo on May 28, 2019, 06:34:59 am ---I just tested it again and it's the same. Probably because it needs less dc component in the signal?
--- End quote ---

Yes, it's probably looking for a + and - signal, and doesn't mind if it's square or pulses as long as it alternately switches between + and -. You wrote on page1 "Amplitude = 12vp-p (+6V -6V )"

As shown on Simon's sims with nothing connected to the output at ~1kHz it outputs a square-ish nearly 12V p-p shape, but at low frequency it outputs +12V and -12V pulses, which is 24V p-p.
But if you don't have the full specs of what the receiver is expecting, and it works...

Simon:
this was a 1V test signal. At 1Hz you only get a few mV whereas at 1KHz it goes nearer 1V, not sure wy as I'd have thought that the rise/fall is what it is regardless of the frequency but that's thhe end of my expertise.

StillTrying:

--- Quote from: Simon on May 28, 2019, 12:05:54 pm ---At 1Hz you only get a few mV whereas at 1KHz it goes nearer 1V
--- End quote ---

It's something to do with leaving the square wave's rise and fall times blank on a long simulation.

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.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod