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Part substitution

R

Randy Day

Jan 1, 1970
0
I want to build this PWM circuit, and I have no
100k pot. Can I substitute a 10k pot and a 1uf
cap for timing, or are there other things I
need to consider in this circuit?

+V|--------+--------|
|-----| |-| | |
_v_ | .------. --- |
-|___|- |-|3 4 8 | ---.1uf .-.
| 100k | | | | | | 10k
- V | 555 | === |_|
^ - +-|2 | GND |
| | | | 7|-------------+-out
+---+--+-+-|6 5 1|---
| '------' |
--- | ===
---.1uf | GND
| ---
=== ---.01uf
GND |
===
GND
(created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)
 
J

jasen

Jan 1, 1970
0
I want to build this PWM circuit, and I have no
100k pot. Can I substitute a 10k pot and a 1uf
cap for timing,

yes, but doing so will increase the power consumed by the 555 circuit.
Also you won't be able to get as close to 0% or 100% as with the 0.1uF
capacitor
or are there other things I need to consider in this circuit?

Mainly the maximum rate that pin 3 can drive current into and out-of the
capacitor.
 
R

Randy Day

Jan 1, 1970
0
jasen said:
yes, but doing so will increase the power consumed by the 555 circuit.
Also you won't be able to get as close to 0% or 100% as with the 0.1uF
capacitor




Mainly the maximum rate that pin 3 can drive current into and out-of the
capacitor.

Good points. Thanks.
 
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