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Chattlab Chattanooga

Re: 24vac to 5vdc sense

Aug 14 2014
Thanks Jason, et al.  I actually have that current sensor from Sparkfun (bought it from Sparkfun).   I'll be just as happy to know from a percentage basis.  I have a adafruit datalogging shield that I'll probably use, as well as some temp/humidity sensors.  If I ever get around to making it, I'll tr

Re: 24vac to 5vdc sense

Aug 14 2014
Relay: Will definitely work. A relay is a nice simple option for quick and dirty, and safe for the sensing circuit. Jeff: That common lead: the 24vac transformer that feeds your thermostat has two output wires.  One is connected to the "C" terminal on your thermostat, the other is the one switched t

Re: 24vac to 5vdc sense

Aug 14 2014
well..... I guess that would work.  Hadn't thought of that!  It would add some isolation too from any spikes. On Thu, Aug 14, 2014 at 1:11 PM, joshua johnson wrote: If you're just trying to sense on/off, why not use a relay? On Thursday, August 14, 2014, Jeff Johnson

Re: 24vac to 5vdc sense

Aug 14 2014
If you're just trying to sense on/off, why not use a relay? On Thursday, August 14, 2014, Jeff Johnson wrote: What I would eventually LOVE to do, is to make a R-pi based programmable thermostat.  And I don't mean programmable tstat in the traditional sense, but rather one you

Re: 24vac to 5vdc sense

Aug 14 2014
What I would eventually LOVE to do, is to make a R-pi based programmable thermostat.  And I don't mean programmable tstat in the traditional sense, but rather one you can actually program in C to do cool things such as checking the internet for weather changes, or emailing me when filters need chang

Re: 24vac to 5vdc sense

Aug 14 2014
Very astute of you, Jason (as always).  Yes, I was thinking of watching my tstat to log inside/outside temps and how often it comes on.  In particular, I would like to eventually make a device that sits between my tstat and HVAC, so when the house is vacant (vacation mode) it activates the condensor

Re: 24vac to 5vdc sense

Aug 14 2014
It sounds like you are wanting to sense a thermostat or similar circuit. If so, have you found a common ground somewhere to sense against? Sensing with 1 wire, and no common ground / reference would require a current transformer or something similar. On Thu, Aug 14, 2014 at 11:18 AM, Jeff Johnson

Re: 24vac to 5vdc sense

Aug 14 2014
The 10K thing is a potentiometer.....  or is that the same thing as a rheostat?  I was thinking I could adjust the pot until I got a around a 4.5 to 5 v output. The pot would only need to dissipate 0.0576 watts (if my math is right (i^2*r) ) Thanks! On Thu, Aug 14, 2014 at 11:10 AM, Joe Freeman

Re: 24vac to 5vdc sense

Aug 14 2014
Your circuit there is essentially a half wave rectifier. I would put the rheostat on the output side of the diode for the below reason- As I recall, your output voltage in this case will be (2 * (24v * sqrt (2) -  .7))/pi, or about 21.6vdc, ignoring the ac ripple and assuming 24 VAC rms input. You

24vac to 5vdc sense

Aug 14 2014
Guys/gals, if I want to read a 24 VAC signal on whether it is on or not and read it with an Arduino.  When I google this, all I get is power supply stuff.  Can you circuit jockeys look at this and let me know if this would suffice, or if not, can you provide a better option? Thanks.Jeff

Re: New to the area, checking to see what's happening at Chattlab

Aug 6 2014
Oh, the other guys were Jimmy (of LOL shield fame) and Mike Metz, an Orielly photographer. On Tue, Aug 5, 2014 at 10:50 PM, Jeff Johnson wrote: Being from San Fran, did you ever bump into Mitch Altman?  My neighbor hosted him and some guys from Make.  He was going to stay at my

Re: New to the area, checking to see what's happening at Chattlab

Aug 6 2014
Being from San Fran, did you ever bump into Mitch Altman?  My neighbor hosted him and some guys from Make.  He was going to stay at my place but the wife was a little concerned so my neighbor Galen took the fellows in, which was just as well as Galen had a lot more cool toys in his lab than I.  This

Re: New to the area, checking to see what's happening at Chattlab

Aug 6 2014
I doubt you would want SFPBFLOCAR in your arena, it's a 220lbs wedge. :) I found you guys through the makerfare linking so I'll be down for that. I'll be sure to check out knoxmakers, thanks for the heads up. https://www.youtube.com/watch?v=wUeHtoMuOEk https://www.youtube.com/watch?v=m1e6unH1JJs

Re: New to the area, checking to see what's happening at Chattlab

Aug 6 2014
David, Nice to meet you. Knoxmakers.org is one of the two makerspaces there in the KNOX. They both have a good rep. Definitely check them out. If you are ever in Chattanooga be sure and look us up especially October 11th for our Mini Maker Faire which will feature our very own homegrown battle bot a

Re: New to the area, checking to see what's happening at Chattlab

Aug 6 2014
Hey David.  We've been live for about a year, have a space and are growing.  We'd love to have you at our space during one of our public meetings, but have you checked out Knox Makers?  They're right next to you. Jeff On Tue, Aug 5, 2014 at 10:00 PM, David Randolph wrote: I j

 

2 Responses to “Group”

  1. T.J. Mitchell says:

    Still want to do lunch/ coffee sometime? Free most Saturdays including tomorrow.

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