Voltage drop across adjustable regulator

Hi guys, been working on a project and I'm using a nerf gun that runs on 6 D-cell batteries(9volts). I have a 13.8 volt 10amp power supply to power the project. If I run the 13.8 volts right to the gun it works great, just a bit to fast and erratic. I'd like to run it through an adjustable voltage regulator I set up, which works good, keeps the voltage at 9 volts but when the gun fires the voltage drops bad, to like 4 volts, obviously causing the gun to barely work. It's happening somewhere across the regulator, any idea why this is or what I could do to remedy it? Thanks guys.

Picture here: http://f.cl.ly/items/1c3Y1b1B1g3r2K3L0E0K/photo%20(7).JPG

It would really help if I could see your circuit but you need to have input/output capacitors connected to the regulator.

Another possibility is that you are momentarily exceeding the current rating for the regulator. Most three terminal regulators have short circuit protection and will shut off the output. With the output pulsing on/off your meter would display the average.

I'll have a picture up soon, Thanks!

Picture can be found here

http://f.cl.ly/items/1c3Y1b1B1g3r2K3L0E0K/photo%20(7).JPG

I tried adding a capacitor before and after, it did nothing...

Critical information needed is peak current requirement of the nerf gun when being fired. If it exceeds the current capacity of the regulator then it is very possible you will see what you are seeing. Also a schematic drawing would be a great help to insure you have everything wired up properly or not. Trying to determine that from a picture of the solderless breadboard is very difficult.

Lefty

retrolefty: Critical information needed is peak current requirement of the nerf gun when being fired. If it exceeds the current capacity of the regulator then it is very possible you will see what you are seeing. Also a schematic drawing would be a great help to insure you have everything wired up properly or not. Trying to determine that from a picture of the solderless breadboard is very difficult.

Lefty

Is there any way I can measure the requirements of the gun with a standard multimeter

Some meters have a peak hold function that would be useful, it depends on your model though.

thegregthomp:

retrolefty: Critical information needed is peak current requirement of the nerf gun when being fired. If it exceeds the current capacity of the regulator then it is very possible you will see what you are seeing. Also a schematic drawing would be a great help to insure you have everything wired up properly or not. Trying to determine that from a picture of the solderless breadboard is very difficult.

Lefty

Is there any way I can measure the requirements of the gun with a standard multimeter

It's can be a difficult measurement, especially if it's a momentary current pulse rather then a continuous current device if you can hold the 'trigger' on. If it was my project I would check out the nerf gun with one of my bench DC variable voltage power supplies that is rated for up to 6 amps max, before figuring out what size voltage regulator device to use. There are some adjustable and fixed voltage regulator chips available that have greater then 1 amp max ratings.

Lefty

Before you do anything else you need to add capacitors to the input and output of the regulator. You should be able to find a data sheet on your part which will show the capacitors needed for proper regulation.

Or else you can try 10uF electrolytics on both pins and see if it just works.

mstanley: Before you do anything else you need to add capacitors to the input and output of the regulator. You should be able to find a data sheet on your part which will show the capacitors needed for proper regulation.

Or else you can try 10uF electrolytics on both pins and see if it just works.

He said he did that in reply #4

Wow! I have no idea how I missed that. <>

If I run the 13.8 volts right to the gun it works great, just a bit to fast and erratic.

You can put diodes like below in series between the power supply and motor to drop the voltage ~.7v per diode to slow the motor down as needed.

http://www.radioshack.com/product/index.jsp?productId=2062591

http://arduino.cc/forum/index.php/topic,117681.0.html