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1  Using Arduino / General Electronics / Re: Circuit Correct? Help me! on: Today at 12:47:03 am
How do you know the capabilities of a battery before you buy? Google! Look on the manufacturer's website.

Unless a battery is specifically rated for high current (like rechargeable Lithium Ion or Lithium Polymer), plan on drawing no more than C/2 where C is the AHr (amp hour) capacity of the cells. C/4 is better.
2  General Category / General Discussion / Re: Generating Square Wave with with modulated carrier frequency on: Today at 12:41:46 am
I don't get the OP's video.
3  Using Arduino / Project Guidance / Re: Help With Powering/Wiring of a CNC-Style Setup on: Today at 12:40:57 am
Yes, that is one of the counter-intuitive things about stepper motors. They may draw less current when they start moving faster.
4  Using Arduino / General Electronics / Re: Circuit Correct? Help me! on: Today at 12:39:28 am




Pin 1 Gate to the BJT
Pin 2 Drain to the motor and diode
Pin 3 Source to V+

Looks OK to me. Change the resistors, change the batteries to something larger.
5  Using Arduino / General Electronics / Re: Getting 0-5V with PWM on: Today at 12:31:11 am
What about average vs peak? I think he wants the average, not the peak.

Anyway, where is the OP in all this?
6  General Category / General Discussion / Re: Generating Square Wave with with modulated carrier frequency on: July 21, 2014, 09:04:25 pm
That waveform is either badly locked on, or there is something going on.
7  Using Arduino / Project Guidance / Re: Help With Powering/Wiring of a CNC-Style Setup on: July 21, 2014, 08:58:43 pm
I bought a bunch of VGA/RAM heat sinks. Just the right size for the A4988. Many come with thermal double-stick tape on them, if not, buy some.
8  Using Arduino / Project Guidance / Re: How rugged is Arduino? on: July 21, 2014, 08:50:13 pm
Short, clear, code. The hardware affects the reliability, too.
9  Using Arduino / Project Guidance / Re: Poll: How Should I Unlock My Door on: July 21, 2014, 08:48:01 pm
DIY RFID?

http://playground.arduino.cc/Main/DIYRFIDReader

As others have said, the unlock mechanism may take your entire $20.
10  Using Arduino / Project Guidance / Re: How rugged is Arduino? on: July 21, 2014, 08:41:55 pm
Quote
Should i use a watchdog timer for reliability?

Yes, absolutely. Never assume that it can be made to never lock up. ESD, nearby lightning strike, stray cosmic ray, etc.
11  Using Arduino / General Electronics / Re: Circuit Correct? Help me! on: July 21, 2014, 08:14:36 pm
Wow! No wonder your AA batteries are pulled down so far. There is no way they'll supply 1.5A at full voltage, or for very long.
12  Using Arduino / General Electronics / Re: Circuit Correct? Help me! on: July 21, 2014, 04:46:12 pm
Do you have a 10A range on your meter? Connect the meter in series with the motor and connect them to the batteries without the MOSFET.

And change those resistors!

There is no point in placing capacitors in the circuit until you either use larger batteries, or find out that your batteries are merely worn out and you replace them.
13  Using Arduino / General Electronics / Re: Circuit Correct? Help me! on: July 21, 2014, 04:26:48 pm
No, get bigger batteries. Capacitors will only make up for spikes in current draw. Fix those resistors, and use larger batteries.

How much current is this motor drawing?
14  Using Arduino / General Electronics / Re: IR Led and Phototransistor connection give always 0 value on: July 21, 2014, 04:25:15 pm
Some phototransistors bring the Base lead out for biasing.
15  Using Arduino / General Electronics / Re: Getting 0-5V with PWM on: July 21, 2014, 04:23:57 pm
An entire industry disagrees with you. Page 44 of the good old Simpson 260 VOM (page 23 of the PDF) has the schematic. No smoothing capacitor when using the ACV range.

http://www.simpson260.com/downloads/simpson_270-4_user_manual.pdf

Same with the 160:

http://www.simpson260.com/downloads/simpson_160_schematic.pdf

Some other brands:







In VU and dB-spl meters, capacitors are added to slow the response time of the meter.

In any case, what I said about peak readings still stands.
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