Hello,
I am trying to make a simple device to calculate when 6 different oil burners are running (120vac each): just a simple binary on (~3-5vdc), or off (less than ~1.1 vdc). It doesn't have to switch in microseconds (or even 2 seconds), just so I can expect how it will run, and it doesn't give me false/unreliable data!
The method that I have been using so far is a radioshack 120vac to
12.6vac@300mA transformer (followed by a few components) for each burner to step the voltage down to a single Parallax oem bs2 pbasic chip, powered (for now) by a 9v battery.With my limited knowlege of electronics, this is what I devised:
For each burner:
-hot->|transf|->(rectifier)(+)->(in )[voltReg]
-ntr->| |->( )(-)->(grd)[ ]->(diode)->(+cap)->pin [ ]->--grnd----| | The ~20ft of thermostat wire runs from each transformer at the burner, to the regulator setup, where all of the retifiers, regulators, diodes, and capacitors are operating in parallel (except common ground and the fact that they each tie into their appropriate i/o pin on the chip) +-[ 9vbattery ] |(Vin) | transformerA ----> [ regulator setup ]-> p1[ parallax chip ] | transformerB ----> [1(fullwvRect100vdc)]-> p2[ ] | transformerC ----> [2(voltageReg +5vdc)]-> p3[ ] | transformerD ----> [3(diode IN4003) ]-> p4[ ] | transformerE ----> [4(capacitor 22uF) ]-> p5[ ] | transformerF ----> [ ]-> p6[ ] | [ ] |(Vss) | [+-common ground-------------+---------------+ | (water line)
Unfortunately, I continue to experience a number of problems:
a) the DC output to the pins to the common ground can be as high as
11vdc...I am hoping (and I thought I designed) a circuit that would give me a fairly stable ouput of roughly 1.5vdc to 5vdc. I think that this is the core problem I am having...how can this be stablized? where is the fault in my design? what can I do to add/replace to give me a target of roughly 3-4vdc for each pin that is *stable*.b) when testing, I touch a stepped down wire to one of the i/o pins on the chip, but for some pins, the chip will just reset immediately, othertimes it will hang in limbo until it recorrects itself automatically (it may be resolve itself faster if I short the pin to ground, but it doesn't seem consistent).
c) sometimes the voltage on the chip's Vdd pin (which should be a clean 5vdc input) can vary significantly, from a constant 5.01vdc for a number of seconds to a whopping 16vdc and even 22-23vdc, but usually one of those numbers. I don't understand why this is happening if I am using a 9v battery to power the chip! (I know that its designed to be an unregulated, clean 5vdc input, but I've been guessing that I can use it to measure the voltage applied to the chip's regulated input pin, Vin. According to Parallax, Vin can receive 6vdc to 24vdc to power the chip). The voltage regulator on the chip is not warm at all.
d) sometimes I will get "phantom" input voltages on chip's pins, especially p6, even if no pins are connected to the transformers. Othertimes, I will get them in steps across the chip (eg, p2,p3, then a few seconds later p4,p5,p6, etc) or in blocks (eg, p2-p6 simultaneously). sometimes just a single pin.
This reduces me to a unstable setup which will sometimes work for a few hours, but then hang my chip until I manually reset it. It also left me with 1 ruined parallax chip (haven't figured out what component/wire failed), and a fried eeprom chip that could no longer be written to....
Specs of the components are as follows:
pcb transformer: 273-1385a; 120vac pri, output(load):
12.6vac@300mA+/-5%; output (no load): 16.38vac+/-5%; current(load): 90mA max; current(no load): 60mA max. (Not sure how they arrive at the current (load) 90mA max...wouldn't it be 300mA at 12.6?)Parallax oem bs2 chip:
Thanks in advance!!! nleducatecareer [ at ] hotmail [ dot ] com