Voltage regulator question

FIREMANJIM

New Member
I am running a 14M2 chip from a 9v battery through a LDO voltage regulator. The LDO puts out 5v at 120mA....
I am having problems with the chip constantly resetting. Can this be due to the 120mA output from the regulator? Or is it most likely in my program??
 

inglewoodpete

Senior Member
The chip is probably resetting due to wiring and/or component selection issues external to the PICAXE.

The most likely cause is if the download circuit is not connected correctly. Second, what sort of 9v battery are you using? The 'transistor radio' type (PP3/006P/6LR61/216 size battery is 48.5 mm × 26.5 mm × 17.5 mm or 1.91 in × 1.04 in × 0.69 in.) is unsuited to delivering 120mA, even for a short period.

Could you provide a circuit diagram to clarify the hardware side of your project.
 

JimPerry

Senior Member
If you are talking about a PP3 style battery, the alkaline version has a capacity of around 600mAH. So for any sensible lifespan you are looking at a useful maximum of around 30mA.

Battery capacity is usually a measure of AH capacity and is based on physical size rather than rated voltage. In essence a large battery has greater capacity than a smaller one of the same voltage and hence may be considered as capable of greater current capability.

As to maximum current, it all depends on chemistry, how long you want to draw current, how much money you have to spend, etc. As a simple rule, I would suggest you use AH/20 as a useful yardstick. The current versus AH capacity is not linear. For example, taking the above example, you might only get 10 hours at 30mA (300mAH) but you might get 1500 hours if you only drew 1mA (1500mAH).

If you have a particular battery in mind, simply enter its model into a google search and somewhere in there you'll get an AH capacity rating (that's what I did to establish the first line, above)

Verbatim from Jackrae at https://forum.arduino.cc/index.php?topic=132106.0 :cool:
 

hippy

Technical Support
Staff member
I am having problems with the chip constantly resetting. Can this be due to the 120mA output from the regulator? Or is it most likely in my program??
It's hard to say. If you are drawing a lot of current or have large current surges, such as when controlling a servo or solenoid, you may be overheating the regulator, causing a collapse of the supply voltage or it to going into thermal shut down, which resets the PICAXE.

Most simple PICAXE circuits, even with a few LED's and other bits and pieces, shouldn't draw too much current, so should not cause any reset.

It could be that there's a circuit error which causes a large current surge when the PICAXE does something with I/O pins which causes a current surge, shuts down the regulator, which causes a reset.

If you have something connected to the Download Serial In pin beyond the download cable; that can cause resets unless a DISCONNECT command has been used at the start of the program.

Another possibility could be that you have a RETURN somewhere which gets executed without a corresponding GOSUB which causes the program to go off in a random direction, which may be likely to give the impression the PICAXE has reset.

The key questions would be; how frequently the resets occur, what you have connected to the PICAXE, and what your program does. Seeing a circuit diagram and the program code may help diagnose the issue.
 

techElder

Well-known member
The LDO puts out 5v at 120mA....Can this be due to the 120mA output from the regulator?
I concur with all of the above comments with the following caveat; the OP didn't actually say his circuit drew 120mA from the power source. The current draw is unknown at present.

FIREMANJIM, the quoted statement shows a little about how you are possibly interpreting (or misinterpreting) current within an electronic circuit.

Most commonly, we say that devices "draw" current from a voltage source. In other words, just because a voltage source (your battery with regulator) is capable of supplying "120mA", doesn't mean that the components of your circuit will draw or pull 120 milliamps from your voltage source.
 

erco

Senior Member
Hard to say without more details, FMJ. Per others, 9V batteries don't have much energy to start with. Test with a known new alkaline cell and a voltmeter across your picaxe power pins to see what's going on. Try to figure out the cause of any voltage drop. Something triggering, switching, button press, etc.

If you have servos, motors, solenoids, or other current-sucking devices, then:
1) add a nice big electrolytic cap (100 uF or better) right at the Picaxe (good)
2) don't power them through the same regulator (better), or
3) power them from a seperate battery or supply (best)
 
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