Show Posts
Pages: [1] 2
1  General Category / General Discussion / Re: Reading Atmel on chip temp sensor on: January 21, 2013, 10:02:04 pm
Looks like lots of stuff, thanks.
2  General Category / General Discussion / Re: Reading Atmel on chip temp sensor on: January 21, 2013, 09:25:24 pm
I have searched but am not sure I am describing the issue properly to find anything.  I didn't find anything.  I guess it could be coded in assembler and it would be nice to not to have to reinvent the wheel.

As I wrote this response it occurred to me to look for a forum for the Atmel Studio users.  It would be nice to know if Arduino ever accessed it.
3  General Category / General Discussion / Reading Atmel on chip temp sensor on: January 21, 2013, 08:19:47 pm
I would like to read the chip temp to be aware of overheating when it is used in a remote location.  In the Atmel manual it has this reference on page 252:

24.8 Temperature Measurement
The temperature measurement is based on an on-chip temperature sensor that is coupled to a single ended ADC8
channel. Selecting the ADC8 channel by writing the MUX3...0 bits in ADMUX register to "1000" enables the temperature
sensor. The internal 1.1V voltage reference must also be selected for the ADC voltage reference source
in the temperature sensor measurement. When the temperature sensor is enabled, the ADC converter can be
used in single conversion mode to measure the voltage over the temperature sensor.
The measured voltage has a linear relationship to the temperature as described in Table 24-2. The voltage sensitivity
is approximately 1 mV/°C and the accuracy of the temperature measurement is +/- 10°C.
The values described in Table 24-2 are typical values. However, due to the process variation the temperature sensor
output voltage varies from one chip to another.

Does anyone know how to do this?
4  Using Arduino / General Electronics / Re: Output pin loading - driving relay coil on: January 04, 2013, 12:56:44 pm
The relay will be driving an irrigation solenoid with the following specs:  solenoid: 24VAC, 370mA inrush current, 190mA holding current, 60 cycles

http://www.sprinklerwarehouse.com/Hunter-Sprinkler-Irrigation-Valve-p/srv-100g.htm

The relay is double pole and will switch both sides of 24VAC at the zero crossing point of the AC waveform.  Is anything needed to handle the collapse of the solenoid coil field?  Is there anything in the solenoid coil at the zero crossing point?

Thanks in advance.

5  Using Arduino / General Electronics / Re: Output pin loading - driving relay coil on: December 29, 2012, 08:42:27 am
Thanks for the advice.
6  Using Arduino / General Electronics / Output pin loading - driving relay coil on: December 28, 2012, 10:07:35 pm
I want to drive a relay that is rated at 28ma coil current.  Do I need anything more than a direct hookup to drive forever for years and years?

Here is the relay:  http://www.digikey.com/product-detail/en/IM03NS/PB1204-ND/1927544

Thanks.
7  Using Arduino / Sensors / Re: OPamp on: October 09, 2012, 03:55:26 pm
If you have three wires coming out, I think you have two resistor elements in the strain gage, one is on the piece of steel that strains, and the other is in another place where it is an offset for temperature correction.

They make up half of a wheatstone bridge.

8  Using Arduino / Project Guidance / Re: Am I overpaying for this? on: October 06, 2012, 05:39:17 pm
Check this on Amazon:  http://www.amazon.com/Arduino-Uno-Starter---Solderless-Breadboard/dp/B0051QHPJM/ref=sr_1_1?ie=UTF8&qid=1349562934&sr=8-1&keywords=arduino+uno+kit

$36 and free shipping if you select the slow super saver shipping.

The Arduino Uno certainly has enough capabilities to do robotics.
9  Using Arduino / Project Guidance / Re: Power from 24VAC on: October 06, 2012, 05:33:19 pm
Thanks everyone for the input.  At this point it looks like the best solution is a DC to DC converter and a bridge and cap.  There aren't many and they are a little pricey but this one looks like it will do the job:  http://www.digikey.com/product-search/en?x=15&y=9&lang=en&site=us&KeyWords=102-1839-ND
It has an 18v to 72v range and is $19.95 q1.
10  Using Arduino / Project Guidance / Re: Power from 24VAC on: October 06, 2012, 06:35:28 am
I looked at Mouser and they start at 80VAC

http://www.mouser.com/Power/Linear-Switching-Power-Supplies/Linear-and-Switching-Power-Supplies/_/N-8s82p/

Same story at Digikey.

Do you have any quick thoughts on a tiny transformer?

Thanks.
11  Using Arduino / Project Guidance / Re: Power from 24VAC on: October 05, 2012, 12:04:57 pm
Thanks for the inputs.

The Recom is a neat device http://www.recom-power.com/pdf/Powerline-AC-DC/RAC01_02-SC.pdf

However, it is rated at 90vac minimum.  What happens when it is used at far below its rated minimum?

I guess that several billion wall module power supply designers are right and that a transformer is the best approach. 

Does anyone have any recommendations for a tiny transformer to go in front of the bridge?

As i looked at information on transformers, it became obvious that becoming familiar with all the varieties and specifications could take a long time.  Does anyone have any quick explanation on how to see the load imposed by the winding on a perpetual basis>

If this post seems redundant, I put one up a few minutes ago that didn't show up and decided to do it again.

Thanks again.
12  Using Arduino / Project Guidance / Re: Power from 24VAC on: October 04, 2012, 04:52:40 am
Thanks for the comments.

Does anyone have any thoughts about induced voltage being used for something like this?  I saw somewhere a small device that I think was meant to measure load on an AC line like an amprobe ?? but used to feed a micro for measuring.

Again also, can someone give their opinion of a tiny transformer.  What is the difference between a signal transformer and a power transformer?

Thanks.
13  Using Arduino / Project Guidance / Re: Power from 24VAC on: October 03, 2012, 06:52:23 pm
That switching regulator is the neatest thing I have seen for a while, thanks.

I plan to try half wave and see how things look.

Thanks everyone for the input.
14  Using Arduino / Project Guidance / Re: Power from 24VAC on: October 03, 2012, 04:01:04 pm
Maybe a tiny transformer.  What is a signal transformer vs a power transformer?

I guess a transformer will also represent a constant load?
15  Using Arduino / Project Guidance / Re: Power from 24VAC on: October 03, 2012, 03:56:48 pm
I just looked and both the 7805 and 7812 say 35v max, and when I hooked up the caps and bridge I got over 40v with no load.  Is there an easy way to knock this down? 
Pages: [1] 2