How to reduce 12v dc to 5v dc

John,

Everything is still on the bread board.

The lipo is powering the LED's and the 9v battery is powering the Arduino board.

The arduino has inputs for 3.3v, 5v, or 9v.

I haven't burned the arduino sketch to the Attiny yet.

I should upload a picture of the tangle of wires I have......

Hi Stanley, I thought that you were already using the Atiny.

John

I have another question.

After reading andrews post about voltage regulators, other than price, is there an advantage to using this,

R-785.0-1.0 - RECOM POWER - DC/DC CONV, 5W, 5V, 1A, SIP | Newark element14 US

or this

LM2574N-5.0/NOPB - TEXAS INSTRUMENTS - IC, STEP-DOWN REGULATOR, 8-DIP | Newark element14 US

as far as quality, life span, heat dissipation?

Stan

stanley thomas wrote:

 

I have another question.

After reading andrews post about voltage regulators, other than price, is there an advantage to using this,

 

R-785.0-1.0 - RECOM POWER - DC/DC CONV, 5W, 5V, 1A, SIP | Newark element14 US

 

or this

 

LM2574N-5.0/NOPB - TEXAS INSTRUMENTS - IC, STEP-DOWN REGULATOR, 8-DIP | Newark element14 US

 

as far as quality, life span, heat dissipation?

Stan

The LM2574 is a single chip whereas R-785 is an entire module.  The module has a step-down regulator chip of some sort inside it, plus the additional discrete components the chip needs such as capacitors, resistors, diodes, transistors, and inductors.  In practice, designing the layout of a switching regulator module is tricky.  Many step-down regulator chips run at very high frequencies -- 1 MHz or more -- and if you don't know what you're doing with the layout it could oscillate and produce an unstable output.  For example, if you put critical components too far from the chip the extra inductance of the PC board traces affect circuit function.

I'm a digital guy so I prefer to leave the analog magic to analog experts.  A module lets you do this.  Some chip manufacturers provide PC board layouts that you can copy.  If you do this faithfully it usually works too.

stanley thomas wrote:

 

I have another question.

After reading andrews post about voltage regulators, other than price, is there an advantage to using this,

 

R-785.0-1.0 - RECOM POWER - DC/DC CONV, 5W, 5V, 1A, SIP | Newark element14 US

 

or this

 

LM2574N-5.0/NOPB - TEXAS INSTRUMENTS - IC, STEP-DOWN REGULATOR, 8-DIP | Newark element14 US

 

as far as quality, life span, heat dissipation?

Stan

The LM2574 is a single chip whereas R-785 is an entire module.  The module has a step-down regulator chip of some sort inside it, plus the additional discrete components the chip needs such as capacitors, resistors, diodes, transistors, and inductors.  In practice, designing the layout of a switching regulator module is tricky.  Many step-down regulator chips run at very high frequencies -- 1 MHz or more -- and if you don't know what you're doing with the layout it could oscillate and produce an unstable output.  For example, if you put critical components too far from the chip the extra inductance of the PC board traces affect circuit function.

I'm a digital guy so I prefer to leave the analog magic to analog experts.  A module lets you do this.  Some chip manufacturers provide PC board layouts that you can copy.  If you do this faithfully it usually works too.

Thanks John,

That helps a bunch.

Stan

I used a micro potentiometer to reduce the voltage.

While using a volt meter, and adjusting the pot between 5 and 6v, the Arduino would not power up.

I'm wondering if the pot restricted the amps to much.

Also wondering if the 5v input on the Adruino is working.

4 AA batteries will give me 6v. Should I use that to test the 5v input, or is 6v too high?

Stan

6V on the 5V line is way too much

Using a POT to reduce the voltage will not work unless it is a very low value as your partly aware,. You don’t say what value your using but it will drop too many volts when the Arduino starts to run and takes more current, the resistor drop will only work at one very specific current, any other current (And it changes all the time due to code and IO) with change the voltage applied to the Arduino

If you’re really determined to use 4 AA batteries and little else then put two diodes in series with the batteries, this will have you operating at 4.8V

A better solution is more volts and  feed through the barrel connector as normal or use a buck boost convertor to give you the 5V no matter the input (Within reason), you could also use a LIPO with a boost convertor or a USB Charger pack, these give out nominally 5V ad internally have the batteries, charging circuit and everyththing already done, they can be found pretty cheaply at most hardware stores.

More fun could be had building up a kit like this one from Adafruit https://learn.adafruit.com/minty-boost or this http://www.adafruit.com/product/1944

Peter

Ok, got the dc-dc converter and it is working great for powering the Arduino at 5 volts, while using the same 11.1 lipo battery for the led's.

Now having trouble burning the Arduino sketch to the ATtiny861a.

Anyone here have experience with this?

Thanks

Stan