# Power limitations?

I was wondering if a arduino mega could power 8 magnetic reed switches and 2 * 5v PIR(HC-SR501) and hook them up to the analog inputs via a voltage divider (5.6k ohm 0.5W & 10k ohm 0.5W) or do I need an external power source to power all of that, if so what would the required circuit look like?

I was wondering if a arduino mega could power 9 magnetic reed switches

A switch consumes no power, so yes.

2 * 5v PIR(HC-SR501)

A PIR sensor consumes very little power, so yes.

and hook them up to the analog inputs via a voltage divider (5.6k ohm 0.5W & 10k ohm 0.5W)

The output of a switch, or PIR sensor, powered by the Arduino will be 0 V or 5V, so you don't need any voltage dividers.

PaulS:
A switch consumes no power, so yes.
A PIR sensor consumes very little power, so yes.
The output of a switch, or PIR sensor, powered by the Arduino will be 0 V or 5V, so you don't need any voltage dividers.

The voltage dividers are to detect if there was a short created: 0v if open, ~3v if correctly closed, 5v if shorted.

From what I understand I would connect:

5v power -----> Reed switch 1 ---> Analog 1 (Voltage divider)
|--> Reed switch 2 ---> Analog 2 (Voltage divider)
|--> .....
|--> Reed switch 8 ---> Analog 8 (Voltage divider)
|--> PIR 1 ---> Analog 9 (Voltage divider)
|--> PIR 2 ---> Analog 10 (Voltage divider)

and code would read values from each input

That seems to make little sense. The only way you'll see 5V on a pin is if the voltage divider is shorted out or there is somehow a short direct from 5V to the analog pin. How are you expecting either of those to happen?

Steve

slipstick:
That seems to make little sense. The only way you'll see 5V on a pin is if the voltage divider is shorted out or there is somehow a short direct from 5V to the analog pin. How are you expecting either of those to happen?

Steve

Tampering via external sources such as a malicious person.

5v ---(long run)-----Reed Switch--5.6kOhm------(long run)-------|---10k ohm
|