Let's Make Robots!

Voltage Regulators

Vendor's Description: 

5V Regulators

Being stupid I can never find out how much resistor and what do i know I would need to get my 7,2V Racing pack battery to turn in to nice 5V that my other components like much better.

Then what makes me happy is when some electronics is simple, like the 5V voltage regulator; You insert "whatever" into it, and out you get steady, steady 5V!!

Note that the large metal-plate is for cooling as it can get hot, so you can put a screw into the hole and put it onto some metal with a larger surface.. BUT! This metal must not be a part of the circuit, I tried that once, strange things happend, smoke..IMG_3397.jpg


Other types

Info on 3.3V regulators and suppliers can be found here.

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What I would like to know is; Why do you need 3V?

.. And then I am thinking that possible the reason that you cannot get a stable 3V is that you should solder some of them blue things over each leg! (Good help, ha?) - I will find out what they are later, I have them laying over in my workshop.

/ Frits

Frits, I think maybe you're referring to capacitors? By adding electrolytic capacitors (values of 10uF or 100uF should do it) from the microcontroller's +V pin to its GND pin you create a "local" power supply for the microcontroller so it can run even if the battery supply drops for a (very) short period of time. In general you should do that with every chip you put in your circuit. When you put in a 7805 regulator you should also add same type of capacitors from the Vin to ground and from Vout to ground. This helps stabilise the power supply. Remember that electrolytic capacitors are polarized and must be put in the right orientation (or it can literally blow up!).

- Jimmy

Well I haven't tried it out myself since I always use 5V regulated by an LM7805 regulator. I was just wondering: is your problem that you can't get the power stable (so maybe your microprocessor or something is resetting all the time?) or that you can't find a 3V regulator - or both?

- Jimmy

I took a look and i am kinda confused about it, What kind of resistors would i need and what kind of Capacitors, I am very new to this part of electronics, the measurements and stuff, Maybe you could help me out with that? Otherwise ill just use two C cells in series. Thanks =)

Maybe you should have a look at the LM117 (datasheet here). It's an adjustable regulator meaning that you can get it to output whatever voltage you'd like as long as it's inside of the valid range found in the datasheet. Remember to add capacitors as seen in the datasheet to make the supply more stable (especially if motors or the likes are drawing power from the battery).

- Jimmy

I have a project im working on and cannot find a stable 3 volt regulator from 9 volt battery. Can someone help me out by telling me what kind i can use or another way of doing what i am trying to do? Thanks I am brand new here and am getting into electronics. =)

Indeed this is one of the most important things in a robot! 

The great thing about voltage regulators is that as long as your voltage supply is above a certain threshold (approx 6 V for the 7805 regulator described in the post) then the voltage regulator will keep a steady voltage of very close to whatever voltage it is made for (7805 is made for 5 V). That's not possible to do just by putting some resistors in series with your battery since battery voltage drops as the battery power is used up.

- Jimmy