I need to design a schematic that produces an asymmetrical square wave with a pulse width of 260 us, Output 0-45mA, pulse rate 1-16Hz from a 9v battery. Any ideas where I can start trying to figure this out?
All of the above circuit suggestions are good but don't address the unusual requirement of ZERO to 45mA output. @Buildacircuit , can you confirm the variable current output? Can you provide a circuit of what this device connects to?I need to design a schematic that produces an asymmetrical square wave with a pulse width of 260 us, Output 0-45mA, pulse rate 1-16Hz from a 9v battery. Any ideas where I can start trying to figure this out?
I assumed that the load resistance would vary to give a zero (no load) to 45mA output.don't address the unusual requirement of ZERO to 45mA output
Yes, since this is Homework Help, and we are supposed to help with your problem, not provide the complete solution, I removed the completed schematic.This was very helpful. I had a question about the schematic you attached though. Did you remove your post?
Yeah, I don't know where folks got the idea that this a homework problem. I'm flattered but long since out of school. I'm trying to build a circuit as a covid project and trouble shoot a device that we use in our physiotherapy clinic (I'm a physiotherapist). If you don't mind putting that schematic back up again I did have a question about it. Are all the v+ symbols connected? I'm trying to reproduce your schematic on texas instruments program t.i.n.a. so I can look at the wave output on the oscilliscope.Yes, since this is Homework Help, and we are supposed to help with your problem, not provide the complete solution, I removed the completed schematic.
What was the question?
The circuit is a 555 astable circuit, triggering a 555 one-shot (monostable).
There are many circuits on the web showing those two types of circuits.
Hi Build.Yeah, I don't know where folks got the idea that this a homework problem.
Yes, all the V+ nodes are tied together.Are all the v+ symbols connected? I'm trying to reproduce your schematic on texas instruments program t.i.n.a. so I can look at the wave output on the oscilliscope.
I really appreciate your help again. I've attached a screen shot of my simulator circuit (t.i.n.a) and the voltage readout over time analysis (virtual oscilloscope). I don't understand why I'm not getting a the waveform that I want. Any ideas why this isn't working? There is a good chance that I made a mistake making the schematic (there is a pretty steep learning curve for a non-engineer). Again I appreciate any help you can give.Ok, if this is not homework (for school), here's the circuit:
Pot U2 adjusts the pulse frequency, and pot U4 adjusts the pulse width.
Yes, all the V+ nodes are tied together.
In LTspice all nodes with the same name are connected together (makes the schematic less cluttered).
Does Tina have a good 555 model?
The one I'm using is transistor based, not just a functional model.
The waveforms shown below should be essentially the same as what Tina's "virtual oscilloscope" would show.
View attachment 257510
150Ω to ground is correct (RLoad in my schematic).150R to 0V
As Eric noted, the time-scale is wrong. Try 2 seconds.
150Ω to ground is correct (RLoad in my schematic).
by Jake Hertz
by Jake Hertz
by Duane Benson
by Jake Hertz