Re: what is trimmer

[Staigen1]

Hi there ateso8634, welcome to this forum

thing named trimmer

They mean a trimpot, it is an adjustable potentiometer, usally adjusted with a screwdriver.

how many junction point it has

It usally have 3 connections, but i have seen trimpots with 2 connectors and also(for special purposes) with 4 connectors.
So, it is an adjustable resistor

//Staigen

 

[ateso8634]

thanks staigen but ı have also one problems
the circuit ı want to build is being used the trimmer(trimpot) with 3 connections but ı have a trimpot with 2 connections  how will ı make the connections?
ı sent the schematic of circuit  R7 is trimpot

View attachment 37623

 

[Staigen1]

Hi

R7 is trimpot

Yeah, i see that, i suggest that you buy the right trimmer for it. Where did you get this schematic, its very similar to a project on this site? And what is the purpose of it?

//Staigen

 

[Staigen1]

Hi

Oops, i found it, it was on this site too! Sorry

//Staigen

 

[audioguru2]

Hi Staigen,
The project's http://www.electronics-lab.com/projects/sensors/016/index.html IR photodiode and opamp circuit is interesting.
At first I thought:
1)Where is the reverse bias voltage for its IR photo-diode, so it can leak current (conduct) when it receives radiation?
2) Where is the negative supply for its opamp?

Then I realised that the IR photo-diode is used in a photovoltaic mode, generating a negative current like a solar cell.
And its parts list spec's a single-supply LM358 opamp that works fine with its inputs at its negative supply (ground). ;D

 

[Staigen1]

Hi Audioguru, we often think the same, i also saw this and reacted at first, and have to look at the datasheet for the ic, saw that it can work at its negative rail and realized that it must be so ;D

//Staigen

 

[walid1]

Hi ateso8634
if you have a 10k ohm 3 terminals trimmer  you can use it instead of the 2 terminals one.
look at the 3 terminals trimmer's terminals, they look like a triangle there is one is far and two close,  connect (short) the far one with one of the remaining two then you have two terminals trimmer as you want.
hope this help you. 

 

[Staigen1]

Hey walid, read the posts moore carefully! ateso8634 already have a 2 terminal trimmer and needed a 3 terminal one! Thats why i recommended him to buy the right one. ;D

//Staigen