Does anyone have a schematic for an easiky built Cap Discharge set-up. Need to operate 5-6 snap switches simultaneously from a rotary switch.
Ric Z
Ric:
Try this link: http://home.cogeco.ca/~rpaisley4/CDPSU.html
Joe
Since there are multiple circuit diagrams on Rob's site, the one you want is the top one under the heading Current Blocking Switch Machine Power Supply. Simple bt effective - it recharges quickly so when you have one of those oh no moments and need to throw a second switch in quick sucession it will work, every time. This is essentially the circuit I built many years ago for my N scale layout and it was simple and reliable. Don't substitute component values, the big resistor is a 5 watt type, which is generally a large ceramic block. It needs to be one of those, heavy current flows through it when charging the capacitor.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Here is one that uses a two filament stop/taillight from a car instead of a resistor. A full wave bridge rectifier and a lots of capacitance. The bulb lights up when the caps are charging and gets dim as they fully charge, plus if you get a short, you know it right away. The resistor and bulb both handle the power but the bulb shows this to you right away.
I like the instant notification.
You can pick up the light bulb and a socket with the wires at any auto supply center, maybe Home depot, Walmart, Lowe's, even some local hardware stores, depending on how they stock. I use Auto Zone in my area.
http://www.hmrg.co.uk/techtops/bigcpu.htm
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
If I remember correctly, Mr. Beasley built his own and at one point posted guidelines or instructions on how to do it. A search may bring up the post. As I used one (that I bought) for a Peco, I'll check my archives and direct you to his post if I saved it.
OTOH, I have the sense Mr. Beasley builds ICBMs in his spare time, so his approach may not be applicable for all!
Rick Krall
Here's a worthwhile thread that contains a MisterBeasley post:
http://cs.trains.com/TRCCS/forums/p/180241/1974429.aspx#1974429
In case the link doesn't work, the subject is "Need a link/direction to a capacitive discharge circuit plan" and the OP was Cisco Kid. It's in this forum.
fkrall Here's a worthwhile thread that contains a MisterBeasley post: http://cs.trains.com/TRCCS/forums/p/180241/1974429.aspx#1974429 In case the link doesn't work, the subject is "Need a link/direction to a capacitive discharge circuit plan" and the OP was Cisco Kid. It's in this forum. Rick Krall
Here the link is active.
Be advised, that one is much more involved than the bridge rectifier, resistor or light bulb and capacitors.
I have built the same as the one in the link but you seemed to want simple.
Take time to look at both circuits side by side.
I said the same thing in that thread, basically. The super simple one, including hte super simple on on Rob Paisley's page, works, but the one that adds the transistor is a better circuit and htere will never be an oops moment with that one because it recharges the capacitor very quickly, makign ot ready for more turnout activations. It is almost exactly the circuit shown in Thorne's book, which is the one I built sometime around 1979. I talk about it a lot, I should retrieve it one of these days and take a phot, but keep in mind I wasl also about 12 when I built it and I just hard wired everythign to the power transistor, no perfboard, so it's kind of an ugly mess. But it was very simple, perfect beginner electronic project, and cheap. And a bargain as once I ntsalled it I no longer blew out the N scale Atlas turnout motors - a couple of those easily paid for the CD circuit.
Thanks. I found a copy of Thorne's book and will review that as well. Would you recommend the High Capacity Discharge Unit he shows, for powering ;5-6 Atlas Twin Coil machines?
I also let a question on the 1.5v lamps in that thread, if anyone wants to take a crack at it.
I haven't seen my copy of the book in years - I think he has 3? A super simple one, oen that has a 2N3055 transistor (I think - anyway, a transistor) and then a fancy one that includes the transformer and is designed to plug in, and I think has a light to show it's charged. If I'm remembering correctly - the second one is the one. Compare to Paisley's circuit. The parts probably are all still available at Radio Shack, although perhaps some catalog numbers have changed since the days of Thorne's book.
Thanks, Randy. I have the third edition of Electronic Projects for Model Railroaders, Dtd 1975. In it, he recommends a hifg-capacity CD unit using a 25v transformer, to power a matrix-diode to conrteol up to 10 machines. He also shows a Quick Recovery unit employing a transistor. (page 37). The high-cap unit uses a 4-5000 mfd capacitor , 2 diodes, a 200 ohm resistor and a 14.4 volt lamp.
BTW, can you tell me what size resistor I would need to drive 2-40ma, 1.5v "grain of rise" bulbs on a 2-battery (~3v) power supply, both in series and in parallel? I need the 3volts to power two LEDs in a project for a contest (n power available), then change the resistors to handle 12v on my layout.
I appreciate any and all help. Electronics are new to me.
RicZ
Modelling Northeastern Colorado (ficticious Colorado Central, Northern Division) area in 1959.
The quick recovery one is the one I built. It easily operated more than one turnout at a time, but I doubt it would do 10 at a time liek the big one. But I only had 8 total on my layout. And I didn;t use diode matrix routes.
If you pout the bulbs in series you theoretically don;t need a resistor. Batteries don't really fluctuate in voltage since it's chemically derived. You could either use two rechargable types, which are typically 1.2V per cell instead of 1.5V, which would run the lights slightly under power, but they would look better and last a lot longer. Or if you use ordinary alkaline batteries, put a 1N4001 diode in series with the lights, this will reduce the voltage to about 2.4, same as using the rechargeable batteries. If nothign lights you probably have the diode backwards, no big deal.
If you put the lights in parallel, either use 1 battery, or you will need a 39 ohm resistor for each bulb.
On the layout wire them parallel, use a 270 ohm resistor for each. This has to be a 1/2 watt resistor (on the lower battery voltage they can be 1/4 watt or even 1/8 watt) and will get slightly warm. Theother alternatice is to use an adjustable voltage regulator, wired for minimum voltage they put out about 1.2 volts, and connect the bulbs to that.
Many, many thanks. I really appreciate it.