# Connecting Components to External Equipment

Discussion in 'General Electronics Chat' started by jgrant333, Jan 27, 2009.

1. ### jgrant333 Thread Starter New Member

Jan 9, 2009
3
0
Hello all,

I have real difficulty imagining how I will connect my devices (such as resistors, transistors etc.) to external test equipment. For example I have to connect a microbolometer (which essentially is a resistor with a high temperature coefficient of resistance) to both a current source and a lock-in-amplifier. However I only have two connections to do so. How on earth do I connect my microbolometer to both my DC current source and lock-in amplifier?

Just to be clear I envisage on wire bonding from my resistor to a PCB and then interfacing the PCB with my external equipment via BNC PCB mount connectors (or something similar).

Also does anyone have a guide on how to understand circuit diagrams? When I look at one I find it hard to even know how to understand what is going on!

Thanks

Apr 5, 2008
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3. ### jgrant333 Thread Starter New Member

Jan 9, 2009
3
0
I've attached an image of what I'm trying to connect.

I realise a 4 point measurement would be a much more accurate measurement however due to space limitations I have to settle for 2 connections to my resistor. In any case the series resistance of the connections is <<< than the resistor's resistance.

I need to supply the resistor with a constant current while meaasuring the output voltage with a lock-in-amplifier. How do I connect these two components when I only have two bond pads?

Many thanks,

James

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Last edited: Jan 27, 2009
4. ### beenthere Retired Moderator

Apr 20, 2004
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If the resistance pictured goes to ground, then it's just a matter of attaching the constant current source and the lock-in input to the other pad. The lock-in will see the voltage across the resistor relative to circuit ground.

5. ### jgrant333 Thread Starter New Member

Jan 9, 2009
3
0
The constant current soure has two leads, one for "high" and one for "low". The resistor must be connected to both these leads. That being the case how do I connect my lock-in amp? Do I just add another pad (see attached diagram) for the input of the lock in amp.

Note I hope to wire bond from each bond pad to a PCB.

Thanks,

James