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1  Using Arduino / General Electronics / Liquid Level Sensor - revisited on: December 02, 2013, 03:52:58 pm
I have read this arduino post:,17338.0.html

and looked through the instructable referenced in that post:

My first question is simple (I think). I am completely ignorant when it comes to electronics - I am learning as I go.
I would like to sense the level of 15 different glass bottles containing misc liquids. I will only need to sense the level of one bottle at a time. Will I need to use 30 IO pins for this? Is there a way to do this so that I can 'share' a common pin between all bottles?
Thanks in advance.
2  Using Arduino / General Electronics / Re: Smoothing PWM for analog output on: June 10, 2011, 02:50:20 pm
I have been looking at a number of them. The A3977 seems promising. Ideally what I am looking for is to control it with Pulse + direction. AND be able to specify the current (100% during motor running, 10% holding current, and disable motor completely). The A3977 specifies 1.6 volts to one pin to run with 1.0 AMP of motor current. So I can do 1.6 volts while running, then .16 volts (approx) for holding current, and also disable the driver completely. My app consists of lifting a load on a ball screw (1 AMP current while running) then holding the load at the top (10% motor current is fine), when in the 'lowered' position disable the motor. Hopefully this makes sense.
3  Using Arduino / General Electronics / Smoothing PWM for analog output on: June 10, 2011, 01:25:23 pm
I would like to smooth the PWM signal to get analog output from the Arduino. I assume that I can do this with a capacitor? I am pretty new to all of this so how do I go about selecting the correct capacitor type/value? I would need 0 - 1.6 volts output. This would control the holding current for a stepper driver.
4  Using Arduino / General Electronics / Re: XBee + Arduino Virtual wire on: June 07, 2011, 09:31:41 pm
After several days of looking it turns out I was searching for the wrong term. I was looking for "XBee Virtual Wire". I was not able to find my answer. After searching for "xbee io line passing" I found it right away. In the interest of helping out if someone stumbles on this forum - here is what I found.
5  Using Arduino / General Electronics / XBee + Arduino Virtual wire on: June 07, 2011, 09:16:42 pm
I have an Arduino+XBee in a base station. What I am interested in doign is having a remote XBee act as a virtual wire. I want the remote XBee to read a sensor on a IO pin, and have my base station's corresponding IO pin reflect the state of the remote XBee. I know this is possible with the Virtual Wire functionality. One problem is how? Anyone know of a tutorial? Also - equally as importatnt is my remote XBee will often be out of range. What happens to the Virtual Wire in that case? Ideally the sensor being "off" will be IO LOW, sensor being triggered would be IO HIGH, and out of range would be IO LOW (same as senseor not 'triggered'). Does anyone know if this is possible?
6  Using Arduino / Microcontrollers / Re: Detecting Water on: May 24, 2011, 04:20:14 pm
Sorry, my bad - I should have been more clear. I changed my setup a little bit. So here is my current setup...

PIN0 pulled to ground with 1M Ohm resistor.
+5V (from Arduino board) placed in bowl of tap water.

PIN0 put in water - it goes HIGH
PIN0 out of water - it goes LOW

Touch PIN0 to my finger and 5 Volts to my finger, PIN0 goes HIGH/LOW unpredictably (this is why I am concerned this 'circuit' is not reliable. ANy thoughts?
7  Using Arduino / Microcontrollers / Re: Detecting Water on: May 24, 2011, 03:32:05 pm
Yes - if I directly ground the pin it works as expected. For grins and giggles I put in a 1M Ohm resistor - this seems to work as I would expect/want it to now. However, I am not confident in it because I simply don't understand all that is going on!
8  Using Arduino / Microcontrollers / Detecting Water on: May 24, 2011, 02:41:40 pm
I have seen a number of circuits that detect water. I am looking for one that is SUPER simple and hooked to a digital IO line of an Arduino. If I put one end of a volt meter on a batteries +5, and the other end of the DMM in the water along with the negative side of the battery - I can measure the voltage of that battery. However, with the Arduino, if I put ground in the water, and a digital I/O line (internally pulled up) in the water also the I/O line does not go down. I assume it can't overcome the internal resistor? (pardon my complete ignorance here, I'm a software guy trying to learn this). Can I instead use some other external resistor to make this work? Thanks all,
9  Using Arduino / Networking, Protocols, and Devices / Re: Arduino + XBee Heartbeat on: May 22, 2011, 12:44:13 am
Thanks for all the info all. Looks like I have a lot if reading to do!
10  Using Arduino / Networking, Protocols, and Devices / Re: Arduino + XBee Heartbeat on: May 21, 2011, 09:38:41 pm
My goal is as few components on the remote station as possible. I guess I need to get more information about the XBee - it sounds like I can write code on the XBee itself. Does anyone have a good reference for what I can do on the XBee? Maybe a tutorial? Perhaps the XBee is even a bit overkill for this particular application but they seem easy to use. The other problem is there may be more than one of these 'systems' around and it is important that a base+remote station are paired - I don't want responses from other stations to interfere with each other.
11  Using Arduino / Networking, Protocols, and Devices / Re: Arduino + XBee Heartbeat on: May 21, 2011, 06:21:13 pm
Apologies for the original crappy title "Arduino".

Essentially what I am doing is I have 1 arduino + XBee at a base station. I want to see if a remote sensor is powered on. That's it - VERY simple. My thoughts were to simply have another XBee at the remote station that sends a heartbeat every second that tells the base station "I'm here and all is well". It sounds like the XBee can do this without the need of a dedicated Arduino at the remote station?

Also - on the remote station can I tie Rx and Tx together? Then when I send something from the base station - it would 'echo' whatever I send? Or am I completely over simplifying things?

Thanks all!
12  Using Arduino / Networking, Protocols, and Devices / Arduino + XBee Heartbeat on: May 17, 2011, 12:27:19 pm
I am setting up one way communication between an Arduino+XBee and another XBee module. I simply need to send a heartbeat from the XBee to the Arduino+XBee. Does anyone know if I can program the XBee directly to send a heartbeat? Or will it need an Arduino to control it also?
13  Forum 2005-2010 (read only) / Interfacing / Re: Hi Power HBridge, DC Motor on: February 22, 2009, 03:02:52 am
Perhaps this is a really dumb question... I know I can double my current capability by using both outputs on a L298, can I use 2 L298's to quadruple my capacity?
14  Forum 2005-2010 (read only) / Interfacing / Re: Hi Power HBridge, DC Motor on: February 20, 2009, 05:26:56 pm
The L298 says it only handles peak output of 3 AMPS. My motor will draw 6.7 Amps when stalled - won't that blow up the chip?
15  Forum 2005-2010 (read only) / Interfacing / Re: Hi Power HBridge, DC Motor on: February 20, 2009, 03:55:55 pm
Oh, right... Duh, the source voltage. Not the lines goign to the actual motor. Ok thanks!
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