Go Down

Topic: Beginner-How many and what voltage power supplies i will need for my project ? (Read 988 times) previous topic - next topic

invader7


And sharing anything with an SD card is just asking for *buzzzzzz* trouble.


i didn't understand this about the sd ! can you explain it ? im planning to connect a raspberry pi in future which uses an sd card...


Any of the boards or sensors need a low noise supply - for instance audio amp?   It's usually a good idea to avoid sharing a supply between digital logic and sensitive analog circuitry to reduce the noise from the logic - for instance a microphone amp should not share supply with
a microcontroller - noise levels of microvolts matter for microphone signals.


So you suggest to seperate the supply of sensors from other supplies right ? The board will be a gsm shield , and the supply/wiring is recommended from the tutorial... the sensors will be humidity digital sensors


If all the devices run at 5V, then you could use one single 5V supply which can provide *AT LEAST* the total amount of current draw for all the devices.

So, for 3 devices which are, for example, 5V, and 1A, 800mA and 120mA respectively, a power supply of 5V and at least 1920mA would be needed, so a 2A would just about do for that.  I like to add a bit of extra for leeway, so a 2.5A 5V supply would work for that example.


So i can have a 5V supply with 1A over the sum/total amps of the items in my project which requires 5V as one group , with A i will not damage something , i will damage only with voltage is that right ?

Thank you allo for answering

dhenry

Quote
the lcd needs 5V@1A.


That's some lcd.

Of them, the fan looks to be the trouble. I would put it on a different power supply, or to put some isolation there (a diode + cap for example).

majenko



And sharing anything with an SD card is just asking for *buzzzzzz* trouble.


i didn't understand this about the sd ! can you explain it ?


SD cards are notorious for inducing huge amounts of noise into a power rail.  I have been working on an audio project (http://sf.net/projects/wavepro) and one of the first problems I had was how to keep the SD card's buzz away from the audio side of the circuit.  The buzz was so bad, if you connected a normal 8? speaker to the power rail through a capacitor you could hear it clear as day.  Yack.
Get 10% off all 4D Systems TFT screens this month: use discount code MAJENKO10

invader7

So you are telling me that if my sensors are analog , i will get wrong voltage by the buzz from other stuff right ? and that i have to avoid it :P like an sd card will effect an analog gas sensor

majenko


So you are telling me that if my sensors are analog , i will get wrong voltage by the buzz from other stuff right ? and that i have to avoid it :P like an sd card will effect an analog gas sensor

It might.  It all depends on the sensors and how sensitive they are to power supply noise.
Get 10% off all 4D Systems TFT screens this month: use discount code MAJENKO10

Go Up