connecting a sensor

Siri

I am attempting to connect a oxygen sensor to my BS2 project.
The specifications of the sensor are 1. a)Power Draw - 29 mW - typial operation @ 3.3V DC input
··························································b)Power Draw - 45 mW typical operation @ 5.0 V DC input
····················································· 2. a)Input Voltage - 0 to +3.3V DC(nomina), w/50mV max. ripple
························································· b)Input Voltage - 0 to +5V DC (nominal),w/50mV max.ripple

The power supply to the sensor is provided by 9V battery attached to main PCB to which the sensor and its
·daughter board is attached to.

The projects power supply has a free power out-let for 9V DC @ 1.5 Amps.

I would like to connect the oxygen sensor(PCB+daughter·PCB/sensor)·to this power out-let.

My question is can I connect ( the battery wires)directly to this out-let or do I require a current limiting resistor if so what value would it be and I would greatly appriciate a good explanation/calculations for arriving to that conclusion.
I have some basic knowlege but I am no electronic Guru - I tinker with electronics and I·am·learning at the same time.

Thank you.

Siri

·

sdy

Can't connect a 5 volt device to a 9 volt supply, will probably damage it. Best thing to do is get a 5 volt regulator. Input goes to 9 volts, ground to ground and output goes to oxygen sensor. Look here for an LM309:
http://www.national.com/mpf/LM/LM309.html#Datasheet

Siri

I am sorry I probably did not explain adequately.

The oxygen·sonsor comes with a main PCB and a daughter PCB - the mother board supplies the daughetr board with regukated 3.3V DC.

The mother board is powered by a 9V battery - I would like to replace the battery power with power from my project power supply - which alresdy has an 9V out-let.

So I will not be connectiong a 3.3V DC device to a 9V DC ·power.



Siri

sdy

Sorry I miss-understood. Then I think you could connect motherboard's 9 volt to your project power supply. The power supply will need to handle that much more power, ~45 mW more, but it should be able to, unless youve got so much connected it's running it at it's limit.