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  1. chopnhack

    Rain Sensor Status

    You are correct, I had remembered the current for the green LED. The red LED is 165microA - the reason for this is I had used 15k resistors instead of 10k - I had to use a 5v input signal instead of the 3v.
  2. chopnhack

    Rain Sensor Status

    Works great on the breadboard, thanks guys!! Here is a final schematic subject to testing on the live circuit. I only have a 7805, but as was mentioned the Vdrop is quite large. I don't believe that much current is being consumed by the circuit, but a rough guess is not more than 21mA for the...
  3. chopnhack

    Rain Sensor Status

    I will give that a go Steve, thanks!
  4. chopnhack

    How to choose a micro controller?

    Thanks Joe, great info - do you have a link for where you got your board, all the ones I find on ebay are Arduino compatible, but they are not the original, they make mention of Funduino, simply Uno, etc.
  5. chopnhack

    How to choose a micro controller?

    Not to detract from the OP's thread, but can you provide a list of resources for both the PIC and Arduino? I am curious to see what you would recommend for someone to get started with Arduino - you made a reference to get some for about $7 - I imagine E-Bay is involved, from my limited searches...
  6. chopnhack

    Rain Sensor Status

    I breadboarded your schematic using DC for the switching signal. As you said, there is a small current leaking from Q2's base. Suprisingly, 3ma was large enough to light the LED! I tried putting a diode in series with R4 to prevent this, but it did not work! I thought diodes were one way gates...
  7. chopnhack

    Rain Sensor Status

    Hi Steve, the incoming signal is when the rain sensor is wet, the NC switch then opens and 3.39VAC is seen. When the NC is closed and the sensor is dry, there is 0 VAC across the switch. I don't know the inner workings of the controller, but I assume that when the terminal of the controller...
  8. chopnhack

    Rain Sensor Status

    Thank you Harald, however as drawn above, I see the switching signal coming in on the left, turning on Q1, which allows current to flow from the top 5v rail through D2 LED to ground, current also flows through R4 turning on Q2 allowing D3 to also turn on. I might not be following the schematic...
  9. chopnhack

    Rain Sensor Status

    Alas, I thought I was close, LOL The 29.2VAC is the irrigation system's power input, I thought it convenient to use it to power the circuit since it was going to be low current consumption (I believe). That is why I am unable to change it. You are right it is too wasteful, perhaps I should look...
  10. chopnhack

    Rain Sensor Status

    I developed an idea after toying with a two transistor flasher :) The components are not completely spec'd I just wanted to get some opinions on feasibility. Taking the input from a normal closed switch with 0 VAC - call that the dry state for which I want a green LED to light up, the same...
  11. chopnhack

    Sinking and Sourcing Current Supplies?

    Does this diagram illustrate sinking and sourcing supplies? My text uses conventional current supply and states that: 1.5.3 A S S O C I A T E D V A R I A B L E S C O N V E N T I O N Equation 1.4 implies a specific relation between reference directions chosen for voltage and current...
  12. chopnhack

    How to setup KVL equations with element laws?

    I don't know the answer. All I can tell you is that 3 is the correct number of nodes per the good folks at MIT. Incidentally, these are the same folks that won't accept my answer for parallel resistance, so take it for what its worth.
  13. chopnhack

    How to setup KVL equations with element laws?

    :P Glad I could entertain you, pass the bottle when you get it... I have pages of equations but not much clarity, when they do a remake of A Beautiful Mind, they can have my desk and papers to toss out the window! The shame is the concept is elusively simple, but I can't get the simple straight...
  14. chopnhack

    Resistors in Parallel

    Just tried that and still no go.. Very strange. I am waiting on some of the TA's to recognize my post. Maybe tomorrow we will have an answer! Thanks for the thought :-)
  15. chopnhack

    How to setup KVL equations with element laws?

    Rest Steve! Tomorrow is another day :)
  16. chopnhack

    How to setup KVL equations with element laws?

    ooh... feel better Steve. Not to worry, I remember there is an additive effect caused by the current source. If I can figure out how to apportion it, I may be able to do more ;-) Rest up and feel better. Thanks again for all your input and guidance. Some progress: with 6v distributed to the...
  17. chopnhack

    How to setup KVL equations with element laws?

    Hey, at least I could figure that out ;-) I have a number of equations at this point, some I have been able to equate and reduce. I seem to need more data to compute - if I had a current I could progress. At this point could I apply ohm's law and split the current supplied from i4 to i2 and i3...
  18. chopnhack

    How to setup KVL equations with element laws?

    Indeed! Some preliminary questions: When you write "then looking at the next...." Where did you come up with i1-i2-i5? Is it a typo for the first line? I found that I had the wrong polarity for i2 - I wasn't following the loop correctly... Aside from fixing that I found that v4 = 6i3 ...
  19. chopnhack

    Resistors in Parallel

    Yes, I tried this: (R*R)/(R+R)+(R*R)/(R+R) I tried this: ((R*R)/(R+R))*2 No avail, I am pretty confident that a parallel resistor equation is (R1*R2)/(R1+R2) I think I will pass it up to the TA's for some assistance.
  20. chopnhack

    Resistors in Parallel

    I tried brackets, parenthesis, no parenthesis - a few variables, tried long form without algebraic reduction of terms... Giggles: a: R+R+R b: R/3 I used brackets here for clarity only. ;-)
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