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16  Using Arduino / General Electronics / Re: How do you make a capacitor bank to amp the voltage of a solar panel up to 5v? on: July 13, 2013, 07:14:34 am
There's a relationship that exists between current and voltage.
I'd suggest you first check that what you want to do is technically feasible with the equipment.
17  Using Arduino / General Electronics / Re: Easiest configuration to power 200 LEDs on: July 05, 2013, 06:29:30 am
You could have one power supply - and have the circuit intermittent by having pins on the wheel strike a PCB on the frame.  Wouldn't be perfect and needs some more thought on how it would wear down...
It would be intermittent at very low spinning speeds
18  Using Arduino / General Electronics / Re: Grounding 5V DC to Earth Ground? on: July 03, 2013, 07:11:02 am
I have this 120VAC to 5VDC transformer on my pcb

I use the +5V side to power my project. Do I have to keep the -5V side separate from earth ground? Also, in the schematic in the datasheet, there is a part that should be tied into chassis ground. Can this just go to earth ground?

Thanks in advance!

Is not -5VDC but rather 0VDC or GND.
Tying that ground to earth is fine in my opinion.
I'd be thinking of how I was isolating that second hot wire actually, it's still an exposed core within the cable.
19  Using Arduino / General Electronics / Testing coil on: June 30, 2013, 12:28:51 am
I've got a device similar to this
or this:

It has a coil in it switched by a triac.
I opened it up and found a 47ohm NFR was blown, so I replaced it with a 47ohm resistor.

I'm not sure if it's working (switching coil on /off), I'm looking for a test to discover that.

If I were to meter the mains for frequency, I wouldn't likely see the coil switching as it still is 50Hz (they claim it uses electromotive force to disrupt noise on the cable to deter pests).
I did feel the coil after around 10 mins of running and it was midly warm, which I think would happen if it was switching, but then.. what happens if you have a coil with active on one side and open for a long period?
I checked the MOV inside the device, it's got very high resistance across it (normal).
I checked the IC (a 14 bit counter) for frequency output to the triac, and this was 1.5Hz.
I checked resistance across coil at 4.7kOhm.

Any thoughts on how you'd test it was working?
20  Using Arduino / General Electronics / Re: 12 volt 30 amp automotive relay on: June 28, 2013, 11:23:42 pm
Test the relay with no loads attached, and that'll rule that out (meter continuity across it if you can't hear the click out of it).
21  Using Arduino / General Electronics / Re: Controlling a 5v relay, only getting 2.4v? on: June 28, 2013, 07:05:11 pm
What's going on at A1 ?
Can I suggest checking voltage across the left side  + / - to ensure you have 5V there?
You say you are losing 2.5V through the transistor, it's connecting to ground, so are you measuring from the E pin to ground? (after the 5V has passed through the relay coil)..?
I wonder if the current to initially pull the relay in is too great? And 42mA is the current to hold it in?
22  Using Arduino / General Electronics / Re: NPN/PNP Transistor on: June 28, 2013, 06:44:38 pm
You've got to stop making multiple threads and focus more on the issue.

You have a Motor (to us, unknown current requirement).
You want to drive it forward / reverse from an arduino.

A properly selected / designed H-Bridge is what you need.
To do that you'll need to know how much stall current your motor draws.
Select a H-Bridge or Transistors greater than that current, and supply it from a suitable supply (not the arduino 5V pin).
23  Using Arduino / General Electronics / Re: Different questions regarding transistors. on: June 28, 2013, 08:25:39 am
There's a nice illustration here:

Note the arduino 5V regulator only serves up little current.. your motor, probably requires more than your USB port can supply.
Transistors help with a related problem (power supply differences).
Look at that image carefully and you'll see what is needed - and how the circuit should work.

Tie the grounds together.
24  Using Arduino / General Electronics / Re: L293D alternative on: June 28, 2013, 06:28:05 am
The chip is going to be a microcontroller to pick up radio, and determine direction based on the RF input..

I've got my eye on J7 in the corner for having output to the motor.. It looks like it could be driving PWM.
25  Using Arduino / General Electronics / Re: How does usb work on: June 27, 2013, 07:32:48 am
Your internet connection has only one plug but you can connect to millions of different computers(!!) does that work?


Broadcast traffic, every packet is sent to every computer one bit at a time. It's surprisingly reliable.
26  Using Arduino / General Electronics / Re: Contact Closure Input module. on: June 21, 2013, 05:31:24 am
Place 5V out, the contact is shorted when 'on' and open circuit when 'off'.

5V ---- Terminal 1 -------- \
IP1 ----   Terminal 2 ------|

If my crude representation above shows it clear enough..
27  Using Arduino / Motors, Mechanics, and Power / Re: Solid State Relay Leakage? on: June 15, 2013, 05:58:07 pm
Solid State relays have leakage. If you want to repeatedly switch something on / off, use them.
But when you want the SSR to be fully off, say after pressing an off switch, a mechanical relay should be across the load to take it off the SSR.

If you aren't switching repeatedly, then use a mechanical relay.
In lights, I would use an SSR with a mechanical relay to drive a strobe effect on a light.
I would use a mechanical relay itself to drive the lights on at night, off in the morning.
28  Using Arduino / General Electronics / Re: connect heater ac 220v 1200W to arduino on: June 15, 2013, 06:57:59 am
Indeed, switch an SSR relay say, 30 seconds on, 30 seconds off, and you'll get temperature control.
Look into how much current the MOC3021 supports and see if you can see why you would not use it in this application.
29  Using Arduino / General Electronics / Re: Not able to interface correctly with LCD on: June 14, 2013, 06:53:36 am
Is it the HD44780 LCD?
30  Using Arduino / General Electronics / Re: Arduino Powers on With Power Applied to Input Pin on: May 18, 2013, 05:26:14 am
Bit of feedback on that photo: that's just a recipe for a short between some of those connections to develop.
Do yourself a favour and get a breadboard to test circuits, and some protoboard / blank PCB so you can lay it out on a bit of board.

Have you got 12V going in on your input? What's the arduino reading the pin state as (i.e. are you expecting high as On, instead of Low as On?)
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