L78L09 Question

[falco_femoralis]

I'm checking out the design for one of the relay bypasses available on the site, and IC2 on this one is a 9v power regulator used to establish VCC for the circuit.

My question is what is the point of having the regulator if the voltage coming in from the power supply is also 9v?

 

[Robert]

It's not required if you'll only power the circuit at 9V.

 

[falco_femoralis]

It's not required if you'll only power the circuit at 9V.

Gotcha, it was included in the design to account for builds which may not run at 9v?

 

[jwin615]

In case inspiration hits and all you have in the studio is a laptop charger

 

[lcipher3]

Not required if the supply is 9v also not recommended if it's supplied with 9v since these regulators need a min of a few volts headroom to work correctly.

 

[Robert]

Not required if the supply is 9v also not recommended if it's supplied with 9v since these regulators need a min of a few volts headroom to work correctly.

It doesn't really hurt anything it just doesn't regulate properly, which is fine since the voltage would be less than 9V anyway.

It's really just a crude overvoltage protection more than anything.