Part 6 - the full circuit

You have so far built all the essential elements you need to measure extracellular signals. You will get the full analog ephys measurement system by adding the filter to the amplifier stage.

Question (bonus): Both the filter and the instrumentation amplifier amplify the signal. What do you think is the advantage of this 2 stage amplification compared to doing all the amplification at one stage?

Exercise 6-1 (bonus) - Use your full circuit to record spikes from a cockroach leg.

For this portion of the lab, if you have been using wall wart power supplies, it may be a good idea to switch to a linear benchtop supply. The TAs can come around with a supply and attach it to your amplifier when you are ready to record since you don't have enough for each group.

• The benchtop supply will provide the same DC voltage values as a mobile phone charger would do. Why do you think it might nevertheless be a good idea to use them? Hint: they are heavy and expensive compared to the little supplies.