reverse sawtooth generator

Thread Starter

mxabeles

Joined Apr 25, 2009
187
is there any simplistic way of creating a reverse sawtooth waveform. Maybe using a network of 555s or some opamp configuration (single sided supply preferably ? I would like to use this as an LFO for a square wave to make a digital kick drum kind of sound.
Thanks,
M
 

Ron H

Joined Apr 14, 2005
7,012

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Wendy

Joined Mar 24, 2008
21,848
An upside down 555? Actually I could do it with a 7555, 2 transistors, couple of resistors and a cap. The transistors are to charge the cap with constant current and discharge the cap, similar how the 555 does it. Basically it is a polarity thing, you're charging to ground instead of Vcc.

An inverting amp after your sawtooth would do it.
 

Thread Starter

mxabeles

Joined Apr 25, 2009
187
great ! great.
one question : sgt., in the schematic there is node with the abrv. IC above it and it looks like the electrical connection is circling around it. What is this device?
Thanks,
M
 

SgtWookie

Joined Jul 17, 2007
22,201
Yeah, the schematic I posted was from a couple years ago when I was still pretty rusty - just happened to think of it and threw it up there.

Max,
that is a SPICE "initial condition" statement. It simply establishes a voltage at the start of the simulation. It would not be in the actual circuit.

I added it because you are somewhat familiar with 555 timers already. It really needs more work before it would be usable.
 

KL7AJ

Joined Nov 4, 2008
2,208
Most function generators also have a "symmetry" adjust where you can twiddle a ramp to be anythng from a sawtooth to a triangle, to an inverted sawtooth wave
 
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