Building simple circuits
One of the joys of model railroading is it provides the opportunity and motivation to learn new skills. One skill many avoid though, is building electronic circuits. I admit circuit building is intimidating, and not terribly necessary since so much is available RTR, but it is particularly satisfying to turn on the power and see things light up (most DIY circuits involve lights) knowing you put that part together from scratch.
You do not have to go to engineering school to learn circuit building. In fact, many ee programs do not include practical circuit building-- all lab work happens on breadboards or in computer simulations. The best way to learn these skills is to get some electronics kits and put them together. If you are a guitar or bass player, an excellent sources for interesting kits is Build Your Own Clone, a company that specializes in classic and cutting edge stop boxes and effects. Their web site is a cornucopia of information-- especially see the "confidence booster" kit-- it doesn't do much (it's a simple volume control) but the instructions are a complete lesson in soldering and parts handling. Another excellent site is Adafruit, which has a section called "learn' with guides to simple and complex projects and topics for the glow in the dark, performance art, Arduino widgets crowd. Another goto resource is SparkFun, which slants a bit more to the robotics fan-- all of the parts needed to build a stepper motor indexed turntable can be found here. Finally, (Definitely not least) is Make, which is a magazine/ publishing house dedicated to DIY in many forms. Their Electronics PDF bundle is a perfect resource for the beginner.
In addition to these, the web has thousands of tutorials and projects including the hobbyprojects.com Model trains section and a site full of circuits from Mark Rollins.
My intent with these notes is to let you get a toe in the water by showing how to build some very basic circuits*, starting with a simple track power detector. I'm not going to teach any theory here, just the actual building skills needed to make a schematic into a board.
pqe
*Suggestions welcome
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All you need is a reed relay with a small magnet that will hold the reed closed but is not strong enough to close it. To operate it you use a bigger magnet external to the car and when you use the opposing pole of the magnet the bigger magnet overcomes the magnetic field of the small magnet and releases the reed. No electronics is needed other than what you are turning on. MR had an article a while back on lighting a caboose and it used this method. Circuitron has one with the small magnet already mounted.
http://www.walthers.com/exec/productinfo/800-9101
or
http://www.walthers.com/exec/productinfo/800-9102
The activating magnet is:-
http://www.walthers.com/exec/productinfo/800-9100
More info is in the Circuitron Catalog but their website is not too good!
Graeme Nitz
An Aussie living in Owasso OK
K NO W Trains
K NO W Fun
There are 10 types of people in this world,
Those that understand Binary and those that Don't!
Almost ..
@Graeme:
Yes, that would be the simple solution except the magnet would have to remain on top or the side of my car or loco during operation. What I was hoping for is a circuit that will turn on with the pass of a magnet and off again the next pass. I can imagine using a push button with a latching circuit similar to activating a stall motor but have not done that either.
Neil
ps if it is 7:30 pm in Hawaii - isn't that 12:30 am in OK? I'm a light weight and can't keep my eyes open past about 9:30!!
Neil Erickson, Hawai’i
My Blogs
No...
...The Activating Magnet does not stay on the car, It is used like a wand. Wave it over the car once which turns it on reverse the wand and wave it again which turns it off.
Graeme Nitz
An Aussie living in Owasso OK
K NO W Trains
K NO W Fun
There are 10 types of people in this world,
Those that understand Binary and those that Don't!
Am I Missing something?
This is from Sparkfun.com. Are there other types?
Neil
Neil Erickson, Hawai’i
My Blogs
Other types..
Yep. The Circuitron product has a second magnet. It's strong enough to hold the switch closed, but not strong enough to close it on its own. The wand has a magnet that supplies the extra pull to close the switch, and the fixed magnet can hold from there. The other end of the wand is a S magnet, and weakens the fixed magnet to open the switch. Neat trick.
pqe
Latching Reed Switches
Neil - I wrote an article that shows a number of ways to do what you describe - see:
http://www.trainelectronics.com/LED_Articles_2007/LED_103/index.htm
The simplest way is to use a latching reed switch - these are rather rare critters - the good news is that I found a source and make them available on eBay. (search eBay for latching reed switch)
There is a short video on my web page that shows how they work.
http://www.trainelectronics.com/LED_Articles_2007/LED_103/LatchingReedSw...
Another article that uses latching reed switches is here:
http://www.trainelectronics.com/LED_Articles_2007/LEDs_for_Coaches/
dave
Perfect!
Thank you gentlemen! That is exactly what I need (er want) to save my li-Po batteries.
On another note, there has been some discussion about Li-Po batteries being dangerous to charge in the car, or engine. I have been using a charger designed for these make by Pololu Electronics and not seen swelling or heating so wonder if this is even a real concern anymore. It is a pain to open the car to remove the battery so charging in place is a real plus. Isn't my cell phone powered by a Li-Po?
Neil
Neil Erickson, Hawai’i
My Blogs
Swelling
The battery in my old Sony cell phone swelled to the point the case would not stay closed any longer.
~Kevin
Appreciating Modeling In All Scales but majoring in HO!
Not everybody likes me, luckily not everybody matters.
IC circuit in a different post?
You stated back in your post on 2015/08/24 Think Inside the box, that the next circuit would have an IC in it, but then this thread went off on a tangent or two. Did you post the IC circuit in another thread?
Thanks,
Other Threads
Yep, several in fact. Click on my username to see them. Note that they are listed in reverse order.
pqe