Jump to content


  • Content Count

  • Joined

  • Last visited

  1. Sounds good to me.. thats the way I will keep it, with no resistors.. Thanks Rob
  2. Ok, that just created a new question. I measured 178ma through the relay coil when activated and so I came up with a calculated 68 ohms for a collector resistor.. but when I put it in the circuit, the relay wouldn't trip any more.. I had to drop down to a 22 ohm resistor before it would engage, and after only a few seconds the resistor (1/4 watt) gets very hot.. don't think that will work well when the pump is on for 5 or 10 minutes at a time.
  3. Thanks for both of your answers, that helps a lot. I will implement your suggested changes.
  4. In examining my fish tank aerator circuit, I am uncertain about the use and value of a couple of resistors. (I acknowledge I am a tinkerer and not an EE).. 1. What is the purpose of R2? is it needed? (I copied its use from a different relay driver circuit) 2. Though they both seem to do the job, how would I calculate the correct values of them? (I just started with them first as is) thanks water pump relay.doc
  5. Thanks for the comments, no I haven't looked at overall power consumption yet.. good idea though. My current thoughts are that since I control the on and off times that I can keep the battery drain to negligible. Might look at your suggestion in the future though.
  6. thanks Rob, those look great, I just ordered some samples from TI.
  7. hi Mike, wow thats just what I was looking for.. My only experience with micro controllers is the TI MSP430 and so I have no knowledge of the PIC systems.. Did it take much programming on your part? Also did that chip allow you to drive a relay directly from one of the pins? My relay has a coil taking about 200ma to activate it so I had to use a transistor.
  8. RobG, thanks for the info on choices other than LM317. I looked at TI and then LT at their stepdown converters, but unless I am reading them wrong, they all seem to be packaged for surface mount. I don't have that kind of accuracy in my tinkering space and so unless they also have some with nice big pins on them I don't know if I can ever use them.
  9. Thanks zeke for the nice pointer to all the relay circuits.. I actually ended up copying one of them for my circuit (now posted in projects). As for mystboy and optocupler, thanks for the idea but it looks like I have found a solution with the parts I have on hand.
  10. Ok, thanks to all of the great help I've had on this forum, I have this working on my breadboard and would love to hear any comments or criticism that could help me turn it into a better circuit or better coding. Warn you in advance that my circuit layout and C++ structure is far from professional. //*************************************************************************************** // Fish tank aerator // final version 1.0 // April 2011 // Built with Code Composer Studio v4 //*************************************************************************************** #include
  11. thanks, I have the voltage reg working now.. used an LM317 circuit.
  12. On my current project I am trying to get the MSP430G2211 to turn on a 12 volt pump for a certain duration. I have all the other logic and coding worked out and done, but I am at an intersection as to how to convert the 3v out signal to control the pump. (see diagram attached).. Do I use some transistor to hit a Power MOSFET (I have an IRF510) and then use that to activate the relay (not sure on how to configure that).. Or do I use the IRF510 or something similar instead of a relay? (never used a MOSFET for anything before).. Or perhaps a better idea yet? thanks.. water pump.doc
  13. infrared, thanks for the interest.. I am making a "live-well aerator control system" for my fishing boat. When I take my boat to Minnesota each year (where I grew up) one of the more popular baits are a variety of live minnows. When I am up at a lake for a couple of weeks, the tendency is to leave the minnows in the boat's live tank overnight along with any late caught fish that I didn't want to clean that night. Rather than leave the tank pump on all night and drain my boat battery, I wanted a way to have the pump come on at selectable times and durations. I first looked at timer chips a
  14. Thanks Geekdoc, I'm sure there are a few of us old players around. My continued amazement is how fast the industry grew and how complex computers are now in everyone's hands including 2 year olds. Its fun to have a circuit and program development environment back in my hands. I'm looking forward to finding new things to make. Before I came to micro-controllers recently, I made lighthouse (to scale) replicas out of wood and mounted on stone and then made an internal battery powered circuit with an LED to simulate a beacon light fading on and off to look like it was rotating.. Then I made a
  15. Thanks for the note about the thumbs up.. I was wondering how that worked.
  • Create New...