|
Science Forum Index » Electronics - Basics Forum » Part substitution
Page 1 of 1
|
| Author |
Message |
| Randy Day |
 Posted: Fri Feb 09, 2007 9:04 pm |
|
|
|
Guest
|
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) |
|
|
| Back to top |
|
| jasen |
| Posted: Sat Feb 10, 2007 2:18 am |
|
|
|
Guest
|
On 2007-02-10, Randy Day <randy.day@shaw.cax> wrote:
Quote: 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
Quote: 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.
Quote: +V|--------+--------|
|-----| |-| | |
_v_ | .------. --- |
-|___|- |-|3 4 8 | ---.1uf .-.
| 100k | | | | | | 10k
- V | 555 | === |_|
^ - +-|2 | GND |
| | | | 7|-------------+-out
+---+--+-+-|6 5 1|---
| '------' |
--- | ===
---.1uf | GND
| ---
=== ---.01uf
GND |
===
GND
--
Bye.
Jasen |
|
|
| Back to top |
|
| Randy Day |
| Posted: Sat Feb 10, 2007 10:50 am |
|
|
|
Guest
|
jasen wrote:
Quote: On 2007-02-10, Randy Day <randy.day@shaw.cax> wrote:
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.
Good points. Thanks. |
|
|
| Back to top |
|
| |
