Re the "earth symbol" on the previous posting website link, with a dual rail power supply that does connect to earth but not many people use dual rail supplies. With a single rail supply, it is usually connected to 1/2 the supply volts - eg for a 5V supply, to 2.5V. To make 2.5V use two resistors. But the value of these resistors needs to be a lot less than the input resistor of the differential amplifier. 1K would probably work, but if you use 10K ones and run it through a voltage follower the reference voltage is more stable. Then, it is a simple matter to replace the two 10K resistors with a trimpot of any value from 1K to 1M. Hope this makes sense and hopefully I will work out how to do ascii art that is wider than the input text window!
Measuring Water level in a Rainwater tank
- Thread starter gmoulds
- Start date
Dr_Acula
Try enclosing your ascii art in the following, use square brackets.
[*code]
art in here
[*/code]
Note: remove the stars, I put the stars in so the {code} & {/code} could be displayed.
Click "Edit message" on someone elses post that contains ascii art if still unsure.
Edited by - Phil75 on 18/10/2006 05:25:18
Try enclosing your ascii art in the following, use square brackets.
[*code]
art in here
[*/code]
Note: remove the stars, I put the stars in so the {code} & {/code} could be displayed.
Click "Edit message" on someone elses post that contains ascii art if still unsure.
Edited by - Phil75 on 18/10/2006 05:25:18
Hi Phil75, thx for the tip. How do I edit a post - is it one of the symbols at the top (eg the 3rd one)? Also, when I try putting in the square brackets, the short lines are ok but the forum text box still keeps wrapping long lines. The text entry box displays differently to the final posting which makes it a bit tricky as well. I might try to squeeze the circuit into the text box as another solution - a narrow long circuit rather than a wide one.
Thanks to Phil75, can now display the circuit for the amplifier. Two inputs go to the two outputs of the pressure sensor. The pot sets the bias. Uses one 324 op amp. Output goes to ADC of picaxe.
<code><pre><font size=2 face='Courier'>
----330K---
| |
| |\ |
|\ | | \ |
| \ | |- \ |
----|+ \--o--10K-----o--| \ |
| / | | /---o--
--|-/ | ---|+ /
| |/ | | | /
| | | |/
--------- |
|
---10K---o--330k-
| |
| |
| |
| |
|\ | |
| \ | |
----|+ \--o-- |
| / | |
--|-/ | |
| |/ | |
| | |
---------| |
|
5v |
| |
| |\ |
10k x | \ |
pot x---------|+ \--o-----
x | / |
| --|-/ |
| | |/ |
| | |
gnd ---------
</font></pre></code>
Edited by - Dr_Acula on 18/10/2006 06:20:02
Edited by - Dr_Acula on 18/10/2006 06:21:10
Edited by - Dr_Acula on 18/10/2006 06:23:08
<code><pre><font size=2 face='Courier'>
----330K---
| |
| |\ |
|\ | | \ |
| \ | |- \ |
----|+ \--o--10K-----o--| \ |
| / | | /---o--
--|-/ | ---|+ /
| |/ | | | /
| | | |/
--------- |
|
---10K---o--330k-
| |
| |
| |
| |
|\ | |
| \ | |
----|+ \--o-- |
| / | |
--|-/ | |
| |/ | |
| | |
---------| |
|
5v |
| |
| |\ |
10k x | \ |
pot x---------|+ \--o-----
x | / |
| --|-/ |
| | |/ |
| | |
gnd ---------
</font></pre></code>
Edited by - Dr_Acula on 18/10/2006 06:20:02
Edited by - Dr_Acula on 18/10/2006 06:21:10
Edited by - Dr_Acula on 18/10/2006 06:23:08