# Designing Circuits with 556 Chips for Garden Railroads



## toddalin (Jan 4, 2008)

There are actually seven steps.

Step 1 - Design the circuit on a breadboard and make it work on a 12 volt battery with LEDs - simple, ~10 parts (including those for regulated power supply).

Step 2 - Supplement the LEDs with relays - Make it work. More difficult, requiring additional capacitors and backwards diodes on the relays. Also requires additional head scratching and filtering to the power supply and chip to stabilize the voltage when the relays kick to prevent false triggering, more difficult, ~15 parts.

Step 3 - Once it works , transfer the components to a perforated board and solder it up. Make it work. More difficult, often requires cussing during the soldering process, same 15 parts.

Step 4 - Change the battery to an MRC 6200 power supply and make it work. (Can be very difficult.). Requires additional capacitors on the relays, additional filtering on the chips, ferrite beads, and lots of head scratching, usually cussing, and hours of "creative experimentation." ~20 parts.

Step 5 - Put the system on the railroad - Make it work. Now we add the "noise" from the train engines, long wire runs for reed switches, also subject to noise, and the elements. Requires revision of the capacitors (typically bigger), the addition of low value resistors to these caps to reduce surge that causes false triggering, and the "creative addition" of additional capacitors, resistors, and ferrite beads to reduce false triggering. Can be extremely difficult requiring hours (days) of head scratching, cussing, and parts substitution hunched over in the garden. ~25 parts.

Step 6 - Put it in the case - Make it work. Can be easy or difficult depending on # of wires (to break or come off) and interconnected assemblies.

Step 7 - Keep your fingers crossed when guests arrive.


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## Semper Vaporo (Jan 2, 2008)

Which cuss words help the most?


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## toddalin (Jan 4, 2008)

Semper Vaporo said:


> Which cuss words help the most?


 
I think that you have to watch MythBusters to find out. I just know what works for me.

http://www.youtube.com/watch?feature=player_embedded&v=pp5hNhHp3Ew


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