Triangle wave generator with NE555

[kishore3677]

Dear All,

Can I get a working circuit schematic of triangular wave generation with NE 555 IC. Frequency requirement is 200KHz.

regards
gvk

 

[mister_rf]

For 200KHz you need to try LMC555 a CMOS version of the industry standard 555 series general purpose timers.
**broken link removed**

View attachment 57738

 

[kishore3677]

Thank you but I need the design values of R and C for getting 200KHz output. What is the purpose of transistor, zener and a diode. Could you kindly explain? And why NE555 not suitable for 200KHz operation?

regards
gvk

 

[mister_rf]

sawtooth wave generator

The part of the circuit consisting of the capacitor C, transistor, zener diode and the resistors form a constant current source to charge the capacitor. Initially assume the capacitor is fully discharged. The voltage across it is zero and hence the internal comparators inside the 555 connected to pin 2 causes the 555's output to go high and the internal transistor of 555 shorting the capacitor C to ground opens and the capacitor starts charging to the supply voltage. As it charges, when its voltage increases above 2/3rd the supply voltage, the 555's output goes low, and shorts the C to ground, thus discharging it. Again the 555's output goes high when the voltage across C decreases below 1/3rd supply. Hence the capacitor charges and discharges between 2/3rd and 1/3rd supply.

The frequency of the circuit is given by:

f = (Vcc-2.7)/(R*C*Vpp)

where:

Vcc= Supply voltage.
Vpp= Peak to peak voltage of the output required.

200Khz that's way too high a frequency for a 555, the timing nomograms give up around 100 KHZ.
Read this topic
https://www.edaboard.com/threads/63288/

 

[kishore3677]

Thank you for the reply. Is it possible to use a crystal oscillator which produces a square wave and connect its output to an integrator and produce a triangle wave output. If yes, can anybody suggest the scheme in detail.

regards
Kishore