hi,

I was wondering if anybody knew a simple way to generate a sawtooth wave that ISNT the method using the 555 timer.

OR

maybe you can help me solve my problem...

i have used a pair of 555's in a circuit im working on as sawtooth (or ramp) wave generators. the problem is i can here a very loud "click" or "pop" nouise on the out put every time the ramp drops from its peak back to the starting point. if you have ay ideas on how to clean up or filter this out it would be appreciated.

THANKS

isolate the power between the generator circuitry and the rest of the audio by using one or two r/c power filters, for example, connect the generator power directly to the battery and then connect a 100-470 ohm resistor in series with the 9 volt power, with a 100UF to ground following it, to supply power to your audio circuitry.

Quote from: slotbothi,

I was wondering if anybody knew a simple way to generate a sawtooth wave that ISNT the method using the 555 timer.

OR

maybe you can help me solve my problem...

i have used a pair of 555's in a circuit im working on as sawtooth (or ramp) wave generators. the problem is i can here a very loud "click" or "pop" nouise on the out put every time the ramp drops from its peak back to the starting point. if you have ay ideas on how to clean up or filter this out it would be appreciated.

Do you mean a true sawtooth, i.e. ramps up then plummets to earth (and yes, you can do this with a 555!), or do you mean a non-linear triangle type wave?

How are you using this circuit with audio? (LED/LDR?).  Are the 555s MOSFET?  Running them at lower voltages reduces spikes, but your problem is probably poor layout.  Is it on a breadboard?

I take it you're using the 555s as LFO?  A little more info would help.

You can also try a larger resistor between pins 6 and 7 in addition to the filtering Zachery just mentioned. Work in the direction of making the cap as small as you can to get the frequency range you want by raising the resistor vaues from Vcc to pin 7 and from pin 7 to 6.

Good luck,
-Peter

I believe you can do it with Smidt Trigger gates or something like that too...Look for the "synth stick" page i think the person that did that project did it that way and ive seen the same thing in the "University of Glassgow Digital Theremin"...sorry i dont have a link.  I think the synth stick had a square wave out but im pretty sure the Digital theremin had a few different waveform outs.

For another way to make a sawtooth wave, search out negistors and then 2N2222s in metal cans.

Use a JFET to buffer the output.

Take care,
-Peter

Try a 7555 rather than a regular 555?

I'm assuming you're using the saw wave as a low freq. modulation source.

There's a neat trick of getting a sawtooth from a 4046 PLL chip. It involves running pins 6 & 7 (pins on either lead of the timing cap) each through a diode, the outputs sum to a buffer.

The LM13700 will do it too. As will the buffered Schmitt trigger oscillator timing junction, or a buffered negistor.

A interestng saw could be made using a square several times the needed frequency and running it into a CMOS divider such as the 4024. The outputs are weighed and summed such that the final wave is a stepped saw which can be left as is or filtered.

The 555 is practically notorious for the discharge glitch. The CMOS 555 gets around it in many ways.

I'm curious - why are you using a 555 for the saw? You can do the same thing with a two-opamp triangle/square generator by using a diode to make one side of the saw much faster than the other.

i wouldn't recommend using a negistor to make sawtooth waves in an unregulated 9 volt circuit... as the battery dies the frequency will drop dramatically and it will stop oscillating relatively quickly (although this is highly dependent on which 2n2222a you select.)  the cmos 555 (7555) recommendation is a great idea for reducing current draw in a battery circuit as well as reducing spikes.  careful, heavy grounding is extremely important for reducing current spikes as well.  i've been solving clock/switching noises in my products for years and every time it's a new puzzle.  good luck!

here's my 2 nanowatts---
a UJT, UnijunctionTransistor will work.
minimal parts even compared 2 the 555.
(which i love bytheway)

the ticking sound is probably not the 555.
it's more likely your amp.
maybe an offset in the saw output V.
output offset is watt makes the pops in all those
4066 & 4016 CMOS switches.
try using cap coupling with a 100K resistor on
amp side of the cap to bring everyything  2 ZeroV(gnd).
staytuned/stay555ed
tone

this has been done with tubes already in the fifties (& I do it now with LM324):
usual integrator/trigger TRI-generator, then invert the tri-wave at its max by help of the internally created SQR-wave.

circuits like that can be found in synth-diy places...

hi,

thanks for all the ideas.

i will try to get some parts in the next few days and let you know if any of your suggestions have had an effect.

scott.