Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Noise issues

Status
Not open for further replies.

Steve Zissou

New Member
HI. Im designing a temperature sensor circuit to measure the heated effect of a silicon photo diode. For the temperature sensors i've used two thermistors, attaching one of them to the backside of a silicon photo diode and the other as a reference sensor on a piece of copper. By illuminating the diode with a laser, the change in resistance in the thermistor will provide a voltage drop different from the reference thermistor. To amplify the difference i've used an instrumentation amplifier (AD620) wtih a gain about 225. But im having noise issues. Any idea where it origins from? The circuit is inside an aluminium box. And input voltage is 5V.

Thanks
 

Attachments

  • drawing2.jpeg
    drawing2.jpeg
    246.6 KB · Views: 143
Sorry. My sketch was a bit unclear. But i do use a positive and negative supply. The gain resistor is 220 ohms and the ref pin is grounded.
 

Attachments

  • drawing2.jpeg
    drawing2.jpeg
    268.4 KB · Views: 125
Can you take a snapshot!! Are you using a scope or just a multimeter.. How much noise is in the circuit... Pots are notorious for noise, try a multiturn trim pot...

Without seeing the noise it's hard to comment!
 
Does the noise have a main's frequency component or other specific frequency, or is it hash (white noise).
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top