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Triangular wave generator

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themaccabee

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Hi,

I need to generate a 10kHz triangular wave 0 to 5V level..
I ve the facility to generate a sqaure wave of desired frequency 0 to 5V level. I just need to convert it to trangular wave form.I ve 555 timer, some opamps if needed. Very tight linearity is not required.Its for testing purpposes..What can be a simple solution?
 

mister_rf

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You may use a separate integrator to generate a ramp voltage from the generated square wave.
The triangle wave's amplitude is set by the ratio of R1/R2.

f OUT = (1/4RtC) (R2/R1)
 

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dick_freebird

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Do you need "roughly", or "exactly" 10kHz?

In ICs I prefer a switched current source and capacitor for timing ramps.
Actually a pair, 1X source + switched 2X sink. Pair of comparators at
3/4*vdd and 1/4*vdd. When ramp gets to top, set FF enabling the sink
current; when ramp gets to bottom, reset. An A=2, ref=vdd/2 op amp
will turn that to a full swing (subject to amp capabilities, amp can be
powered off wider rails) 0-5 t-wave.
 

LvW

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Hi,

with emphasis I can recommend the circuit as proposed in #2 by mister_rf.
It is simple and reliable. It is a derivat of the well known Schmitt trigger oscillator (astable multivibrator).
 

themaccabee

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Thank you all for the suggestions,
I'm thinking of 2 op-amp circuit. By the way in the NE566 solution , if Im operating on single ended supply the output is typically 2.4Vpp. Is that referenced to ground that is 0-2.4V or if itsnt how to convert it to 0-5V scale?
Regards,
 

KerimF

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Do you have rail to rail opamp? If you do, then the circuit of post #2 will be a good choice by adding a virtual ground at 2.5V.

Added:
For instance, the difficulty of your problem is that your supply is 0-5V and you look to have a triangular wave also between 0-5V. At the two peaks, there will be always a small non-linear region.
 
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themaccabee

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Okie i was checking the LM358 dual opamp to build this circuitry , i looked into the datasheet and saw a transistor connected in the VCO circuit.
Can some body tell me what is the exact purpose of the transistor??
 

leo_o2

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It is used to discharge the capacitor.
 

ea.arun

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since the opamp inverting input is a constant voltage the feedback capacitor requirers a constant current dishrge......
this is achieved using the transistor.Capacitor disharges till the next threshold/reference value.
 

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