12v voltage regulator

[andrew2022]

i have 12v coming into a circuit, but it mite have the occasional spike so am gonna use a 12v reg. do i need to connect in to the in to the spll, out 2 the circuit and ground to ground and have a cap on either side? also what values would you recommend (max amps is 1a)

 

[Nigel Goodwin]

i have 12v coming into a circuit, but it mite have the occasional spike so am gonna use a 12v reg. do i need to connect in to the in to the spll, out 2 the circuit and ground to ground and have a cap on either side? also what values would you recommend (max amps is 1a)

Any linear regulator requires headroom, even LDO (Low Drop Out) ones, so you can't have 12V in and 12V out. Assuming you're talking a car battery?, it's usual to run sensitive electronics at less than 12V, to give room for a regulator.

You could use a switch-mode regulator, but these are more complicated and expensive.

What are you actually trying to do?.

 

[andrew2022]

for a power supply where 1 source is battery and the backup is mains so the input would prob be bout 13-14

 

[Nigel Goodwin]

for a power supply where 1 source is battery and the backup is mains so the input would prob be bout 13-14

But what are you feeding?, how stable does it need to be?.

You would usually use a regulator on the mains part, but no need on the battery part - a 12V battery should be stable enough anyway. Also, if you are concerned about mains spikes, you should take them out (as far as possible) with filtering on the mains side - although short duration mains spikes shouldn't have much effect on the rectified and smoothed output from the transformer.