Longbow

MavericK96, on Sep 8 2010, 06:22 PM, said:

I will try to get some current draw readings as well, if I can.

EDIT: Just did some current tests. In my test, using 6 well-charged alkaline D batteries in the battery sled, the current draw was anywhere from 1.0A to 1.6A. It was not very consistent, though in fully-auto the first shot seemed to be closer to 1.6 Amps, while the subsequent shots were closer to 1.1 - 1.3 Amps. Sometimes there would be a random spike of 1.5 - 1.6 Amps after a few full auto shots were fired.

So for example, a readout while firing fully auto would be (each readout is about a 0.5 second time interval):

1.6
1.4
1.1
1.1
1.3
1.2
1.4
1.1
1.5
1.6
1.2

Something of that nature.

The variation makes sense, the motor isn't going to be doing the same amount of work at all times. Drawing the bolt back will take more power than in between for instance. That is still a surprising amount of current draw though. Thanks for doing the tests. I need to crack one of these open, but our walmart still has them flagged as not for sale.

MavericK96, on Sep 4 2010, 01:53 PM, said:

Also, thanks for the new info regarding voltage. I wonder if it would work well to get a 9.6v pack connected in series with a 7.2v pack, for a total of 16.8v, which is right around your recommendation. I was considering getting another 9.6v pack in series, but that would be closer to 20v and probably too fast for the darts to load reliably.

Just a heads up to anyone considering this, mixing batteries is generally a BAD idea. Especially true for rechargeables. Try and keep them the same (Voltage, Amp-Hours etc.). When you are using mismatched batteries, they can drain at different rates and can "empty" at different times. This can confuse the sensors built into the batteries and cause all kinds of unpleasant surprises. They most likely aren't going to blow up, but it's better to be safe than sorry.

Go higher than what you want with your voltages, then bring it down to where you want in your circuit.

Can anyone with a Multimeter check the current draw on the stampede? I'm a bit curious.

CaptainSlug, on Sep 13 2009, 02:22 PM, said:

Use a multimeter to measure your source voltage.
Then just use an LED calculator to figure out what value of resistor you need to use.
http://www.hebeiltd....stor.calculator

Your guide is a tad too overwhelming to be a good introduction to basic circuits.

Thanks for the link, I was going to try and track down something along those lines. Based off of your comment I have also added a preface of types with a quick guide to adding an LED using that calculator.

Phibonnachee, on Sep 9 2009, 09:13 PM, said:

Wait, if V=i*r, what happens if r=0?

Does i represent how many amps can pass, or how many are absorbed.

Arconious has it completely right. In theory as your R gets closer to 0, your current would approach infinity. This obviously isn't possible in a real world situation however since everything has some resistance. As far as a normal wire goes, it can be assumed to be 0 unless you are talking about miles of wire.

The I in the equation is how many amps will be drawn by the element you are looking at. One thing to remember is that current is never absorbed, the same amount of current will be flowing at the beginning of the loop as at the end of it, regardless of how many components there are in the circuit. The voltage potential is what will drop at each element, which is the "voltage drop" I referred to in the first part.

Quote

As a student of physics last year, I understand the general concepts behind electricity and the electronics, but the peice of electronics I want to add to my gun is a bit more complicated than A LED. Would you mind if I PMed you with a few questions?

You are welcome to PM me, but if it is a question that may help someone else down the road you might as well ask here. I will answer to the best of my ability.

Hipponater is completely correct here. The amount of current going into the LED will always be the same as the amount of current coming out.

I have been seeing questions about LED's and general circuit design questions, so I am going to make an electronics questions and answers thread. I'll link it once it is done.

EDIT:
Here is the link to the guide. I have finished the first section, and will be continuing to add more as time goes.
Electronics Guide