Project using a DS1804

MaryMc2009

· Hi, my High School Computer/ Robot teacher has given us a challenge to build a project and solve a riddle using the BS2. ·The code writing shouldn’t be a problem, it’s the actual design and construction I will have problems with, and would like to see if someone here could POINT me in the right direction.
·
· The riddle is a box with two wires leading from it into a smaller box (approx 18 inches of wiring) First wire is BLK, the second is RED
·
The clue we have been given are:
EOL
·
· After a Google search, I figure it’s End of Line resistor. ·So now the team must use a BS2 to determine if the circuit has a EOL and if the switch is N/C or N/O in order to separate the two boxes. ·
·
1.· If the circuit is N/O I should read on the DVM, the voltage in the wire
2.· If the circuit is N/C I should read on the DMV, 0 volts
3.· If the circuit is N/C with EOL in series what would I measure in volts?
··········· a.· If N/C with EOL I will read V drop across R
··········· b. Voltage across EOL may seem like N/O switch
··········· c. A reading of current will show on EOL and not N/O contacts
··So I assume (the start of failure begins with those three words) that it is like a window comparator that keeps one from just shunting the two wires and walking away with the box. ·If so, would I be able to use a BS2 with two maybe three Dallas 1804 100K digital trimmer pots one in series with the EOL the other in parallel, I should be able to substitute out the EOL by using Ohms Law and increase/decrease the series resistor and the parallel resistor to mimic the EOL value with the Dallas 1804 pots without violating the window comparator…is this possible?

· Thanks,
· Mary

Mike Green

I would caution you about interpreting a clue like EOL too quickly. End of Line may be what comes up in Google, but that's usually used in reference to a line of text, like end of the text line, not in reference to wires. It might still mean End of Line, but that's not an obvious reference. You didn't mention a switch and it's not clear from your description where you could even connect to the wires (without removing the insulation). Are you working with other clues or descriptions that you're not explicitly describing? It always helps to make a list of what you know or don't know when you are working on a puzzle.

MaryMc2009

Mike,

· EOL was the only thing on the hint line

· But looking at the task at hand, detach the smaller box from the larger box, I'm going with the thought process of some switch in the small box...maybe a mercury switch? or a trembler....too easy if it was empty.· And to have two wires exposed and running to the other box?· Too easy just to hook a DMV up and read the Volts on the line....either cut if N/O or shunt and cut if N/C.· So I don't know if there is an actual switch of some sorts in the small box....just seems too simple.·



· I also found a mistake in the drawing I posted, if the two pots replace the EOL, and I cut the wire above the two pots, the resistors are no longer in series/parallel but become a straight series connection, adding to the resistance



Mary

Mike Green

You know, EOL could stand for Electro-Optical Link or Even-Odd Line too.· Regarding the wires, are they insulated with red and black insulation?· Are the boxes opaque?· Are there any connections going into/out-of the boxes other than the two wires?· Is the definition of the puzzle that you have to separate the boxes using the tools at hand (like the BS2 and DS1804)?

Franklin

I don't see the challenge. You have the two boxes and the wires connecting them but no challenge. What is it he wants from you at the end of the challenge?

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- Stephen

Bruce Bates

Gents -

EOL resistors are used in the alarm industry. They permit an alarm system to ensure that there is "continuity" in all perimeter circuits. These are generally parallel circuits where the alarm indication is made by "shorting" the two wires. The fire detector, smoke detector, or heat sensor provides the + to ground connection.

A circuit shows "trouble" if there is NO voltage on it, as the circuit is open. A circuit is "okay" if it shows (voltage - EOL voltage drop) on it, and "alarm" if the circuit is "shorted" or shows full voltage. It's kind of a cheap method to provide a quai- tri-state condition without much in the way of external components. It will also work with both electro-mechanical sensing means (multiple sensing relays in consort) or with a micro-controller.

I hope that's helpful.

Regards,

Bruce Bates

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