Hey guys, any of you know how to wire up the electronics in a loco for 1.5 volt DC bulbs??? Reason I ask is. I'm custom building a SD-80MAC from a RPP shell. BUT I want to use the actual light bulb as the lens! So, that means, 2 bulbs for the head lights, 2 bulbs for the red marker lights, an 2 bulbs for the rear reverse lights, an then 2 more red bulbs for the rear marker lights. Each bulb is 1.5 volt DC, thing is I need the red marker lights ones to burn in all directions, the head lights to only burn in forwards, an the rear reverse lights to only burn when the loco is in reverse. Thing is, I have to keep the voltage to 1.5 volts, an also have directional control with diodes (which I know how to do), I just don't know how to cut the 12 volt DC to 1.5 volt DC.... For each bulb. Anyone have an idea of how to do this ???? Any help will be appreciated! [ 01. September 2003, 04:36: Message edited by: 7600EM_1 ]
To my best knowledge as far as I remember from my study (15 years ago) there are at least three possibilities: possibility 1: Try with a powerregulator of 3.3V as I do not think regulators with less output-power are available. At the output of the power-regulator, add 3 normal silicium diodes in flow-direction as that should decrease the outputpower by about 3*(0.6...0.7V) which should get you a bit below your requirements. possibility 2: resistor of sufficient power-consumption in series with the 12V, then Zener.Diode with 1.5 V (althopugh I´m not sure if thoses are available) in parallel with the ends. If Zenerdiodes of the required voltage are not available, normal silicium-diodes may be used (in reverse polarity). possibility3: resistor of sufficient powerconsumption in series with 2 (better 3!) silicium diodes. mount the 1.V buld in paralell with the Anode of the first and the kathode of the last diode. Remember the each diodes consumes about 06 ... 0.7V. remeber that whatever you do, 12V-1.5V=10.V has to be converted into heat!!! Thus do not burn down your railroad (things work well on the workbench as sufficient air surrounds the devices but as soon as the stuff is mounted within the small luttle loco, the loco itself is facing a problem!!!! Be warned!!! Exchanging the bulbs with ones of the propper voltage probably is not possible, or ?!?
No, these are most likely 1.5v microbulbs at about 15 mA. Here is what I would do. Wire all the lights in parallel pairs (this way if one burns out, the others will still work - voltage stays the same in parallel, current stays the same in series). You will therefore need the following for a resisitor: V=IR so 12v-1.5v = 15mA*2bulbs*R This results in R = 10.5v/30mA = 350 Ohms. P=I^2R so the power rating is 30ma^2*350 This results in .315 Watts which is close to a 1/4 Watt resistor, but I would go to 1/2 Watt if I had the room. Don't forget to take into account the slight drop from the diodes for the directional lighting.
Corey, Your right they are microbulbs! They are Miniatronics, 1.5 volt 15mA 1.2 mm diameter bulbs! So... that means one bulb for each opening for a head light lens (I want to use the bulb itself, as the hed light lens in the loco) Which I need 2 clear bulbs for the head lights, 2 clear bulbs for the reverse lights, an 2 clear bulbs for the ditch lights. THEN I need 2 red bulbs for the front marker lights, an then 2 more red bulbs for the rear marker lights. I need the marker lights to burn in both forwards an reverse SIMPLE! I need the head lights to burn in only forwards! SIMPLE! Then I need the reverse lights to burn in only reverse SIMPLE. The ditch lights I THINK need to only burn in forwards????? (I'm not sure about this one) Being I need to have 2 light bulb consists, that means I need to cut the 12 volt to 1.5 volt PER bulb. NOW is is possible to run 2 bulbs wired together at 3 volts for the SET of bulbs ???? Corey, any chance you have a basic diagram of what I need to do with the resistors??? And wherre to put them, along with the diodes???? I'd e-mail you my home address if theirs no diagram online for it so that I know what I'm doing.... As for the resisitors, an all.. any chance of you giving me part numbers for these from Radio Shack? PLEASE, feel free to e-mail me with the e-mail link in my signature! This is a totally custom lighting system I'm doing an these bulbs are expensive (even tho, I got them at a good price for 6 packs of 10 bulbs!) I don't want to blow them! All this lighting will be inside a RPP SD-80MAC I'm custom building.... I want it to look sharp as far as lighting goes, plus be in CSX paint... Will be #801 when its all said an done with....
John, here's what you need to do, at least that's how we'd do it in aircraft. Maybe you modellers have something to replace relays, but if not, use em. This is a little expansion on what Corey said, but heck we're both from RPI, so how could you go wrong?
Jim, I'm sort of lost here! HA! (not hard to do sometimes with eletronics!) The voltage dividers, I take it those are diodes? correct? The relays is what I'm not sure of (Maybe I have it confused) I can see this is going to be a long process, to learn how to lower the voltage to 1.5 volts an be directional. So, with the end effort, will be WELL worth it in the end as the result! But the names of things, with voltage dividers, relays, resistors, an the diodes themself! This all will prove interesting... But the end effect will be the result I want.. I'm just sort of lost here... Jim I see how you have the diagram written out, all is simple, but the names of things, when I go to get these eletrical components, what names of parts an values of things do I look for?
John, the 350 ohm and 50 ohm items in the voltage divider are resistors. I didn't try to figure out what power rating (watts) you need, because I didn't know how many bulbs you had in each circuit. The relays can be considered to be switches that are activated by a signal (forward, reverse in this case). The switch is closed when the signal is present, open when not. As far as the voltage divider resistors go, the value in ohms determines how much voltage drops in each one. 350 is 7 times 50, so of the 12 volts, 10.5 are dropped across the 350 and only 1.5 across the 50. Hope I'm not losing you here. Now I don't know where diodes would come into play, as they block current flow in one direction and allow it in the other direction. When you go to reverse, does the voltage change polarity? Goes from + 12 to -12? If so, diodes would work in place of the relays.
At the risk of revealing my electronics stupidity, couldn't the relays in Fitz's circuit be replaced with diodes? Yes Fitz, the polarity changes when direction is changed. So, diodes mounted in the proper orientation where th relays are shown should light one set or the other of the headlights. What is the proper orientation? If they don't work right, flip em! What size diodes? When in doubt (all the time!) use lmf diodes. (Large mother ... diodes) Gary
Jim, Yes the relays can be replaced with Diodes being the voltage does switch from +12 to -12... That will work.... So, The 350 Ohms are the restistors... My questions is, what do I look for to buy 350 ohm resistors? Just look on the package for 350 ohm resistors or???? Is their a special name for them? as the 50 Ohm ones as well.... Its all making sence to me now! As for the diodes go, your basic sized ones, will work being they are only holding 12 volt DC around 2 amps back.... I use them alot.... And have no trouble with them for 12 volt.... [ 05. September 2003, 03:42: Message edited by: 7600EM_1 ]
John, to be honest it has been so many years since I messed with this stuff--I used to get my resistors by taking old radios apart. I suppose you can buy them at Radio Shack or maybe even at a train hobby store. Back in Genesis, I would look for one with the first three colored bands of orange(3), green(5), and brown(X10). Then one of green(5), black (0) and black (X1). 5 watt ratings would probably be high enough. How many bulbs at 15 ma are in the circuit? As Corey said, add up the bulbs X .015amp to get the total current, then total current (I) squared times the resitance will give you the power consumed. Double that for the power rating of the resistors.
Jim, SHHHHHHH don't tell our secret! I do the same thing to this very day! I rip old Radio's, CD player's, Record players, 8 track players (I love these ones!) VCR's that are junk for the diodes an resistors with a color cose of Brown/Black/Red, not sure of the values of them, but I do know they are whats needed for LEDs to light off 12 volt DC!!!!! And thats how I get alot of it.. Now, for the job I'm doing, I'm going to go an buy the resistors needed! As for how many bulbs, 8 total! Maybe 9 with adding a cab interior light (to see inside the cab windows) ALL are 1.5 volt DC bulbs!.... Only the head lights an the tail lights will be dirrectional (maybe the ditch lights) As I'm not sure of the ditch lights need to be directional (only in forwards) or if they should burn at ALL times, forwards an reverse. But the "red" marker lights wilkl burn at ALL times forwards AND reverse all 4 red bulbs! And then the cab interior light will be hooked into this run of bulbs too being they will all burn in both directions. BUT I do need assistance on these all. I know the head lights need to burn in forwards ONLY! The rear lights need to burn in reverse ONLY. The marker lights and ditch lights I believe burn at all times in both direction front an rear (someone corect me here!) BUT the ditch lights will ONLY be on the front of the locomotive. Someone got insight for this one???? As I'm not sure if the ditch lights are only on in forwards, an are shut off in reverse or they burn at ALL times! Anyone!?
The resistor or voltage divider is really only good for a constant load (current). You should treat each set of lamps that work together separately - ie. each group should have its own resistor(s). The only exception would be if your forward and reverse groups are the same (say two bulbs in each) when the resistor(s) would be the same value AND only feed one set of lights at a time. The reason is that the voltage drop on the resistors, and hence volts at the lamps, varies with the current. I'd be inclined to use the voltage regulator or zener diode ideas as you could achieve constant brightness lights (at the expense of a higher motor starting voltage). That is one reason why 1.5v bulbs are used by some manufacturers. I could probably sketch this for you if you are interested.
John, I can't answer your question about ditch lights. Brown(1), Black(0), Red(X100)=1000 ohms. Using the voltage divider, worst case all lights on at once, you will need 10 watt resistors. I would "mock it up" on the bench first and see how it works before installing in the engine. Good luck.
Mike, I'd be interested in seeing a diagram of the voltage regulator an all, but my question is, I would ALMOST have to mount that to something to disapate heat being thats how the voltage is regulated, an then even if I'd have a place to mount it to, how hot would it actually get. As for the 350 an 50 ohm resistors, I would imagine that they would be mounted BEFORE ALL the light bulbs to cut the voltage to them to 1.5 volt DC. and then control each set (2 bulbs per set) with a diode to make them work by direction of electrical flow. Jim, What would I need a 10 ohm resistor for??? I think I may have confused you alittle. I do some lighting with LED's for like signals an such, not on my engines....But I use the 1000 ohm (brown/black/red) resistors for the LED's only. As for making it all up, It will be made on the bench, then tested before I install it in the locomotive, an won't be installed till I have it to work, how its ment to be.... Just like the real ones! Then once I learn this extra electronics, I may go around and add this lighting to all my "basic" loco's for that added realism....
John, you don't need a 10 ohm resistor. I was just trying to explain the color code. Yes, the resistors go across the power supply source before the bulbs. Try just mounting the resistors with no load (bulbs) and measure the voltage across the 350 and across the 50 to prove the theory. Once you add the load (bulbs) then there is a heat dissipation thing with the resistors, too. If they get hot, try a higher power rated resistor (higher wattage).
OK, forget the regulator - that's going to be complicated. My suggestions are below, at least to try on the bench. (This is going to take some time and I need to cover a little theory so you have a chance to understand what is happening, so get a stiff drink now.) Before starting I would like to say that using resistors in anything other than a "1 resistor to 1 bulb" ratio is courting problems. Resistor voltage varies with current, so adding a bulb will make all go dimmer, while removing a bulb (or when one blows) will make all the others brighter - possibly for quite a short time ... For what John is trying to do, System 1 shows the basic principle of using diodes. Most people know that diodes (the triangular things) only conduct in one direction. Less well known is that when they are conducting they also 'drop' some voltage (referred to as "Vf" (Volts forward)) and for our purposes it is a constant amount. For standard (silicon) diodes the drop is usually about 0.7V. The effect is that when you put a diode in series with a load (eg. a motor) and gradually increase the supply voltage, nothing will happen (no current flows) until the supply reaches 0.7V and the diode begins to conduct. At 0.8V supply, the load will 'get' 0.1V, at 12V supply the load will get 11.3V, etc, with the balance of 0.7V always being across the diode. Put TWO diodes in series and the drop is 1.4V, so the load gets nothing until the supply passes 1.4V, and at 12V supply the load gets 10.6V. This is the situation in System 1 below. There are 4 diodes for the motor because we have to be able to go in either direction. (And yes, if that looks familiar, you can use a bridge rectifier.) Now consider the lamps in the 'Always' group. They are connected across the diodes, so as long as the voltage to the rails is 1.4V or more they will have 1.4V supplying them, which is fine for most 1.5V bulbs. (Most power packs don't supply pure DC, so the action isn't always this exact.) There are two advantages here - more or less constant brightness and (within reason) it doen't matter how many bulbs you have. To get our directional lights we use diodes in their more usual function - the two unfilled symbols show these. But there is a catch (isn't there always?). These diodes will also drop volts, so if we use standard diodes the lamps in these two groups will only get 0.7V supplied to them. A possible solution is to use specialist diodes with a very low Vf of perhaps 0.1V. This will give the lamps 1.3V which is probably OK, but obtaining these components may be difficult, and is a nuisance if you just want to play with stuff you already have to hand. So here is an alternative - System 2. Here we have added an additional pair of diodes in the motor circuit so that a total of 2.1V is dropped before the motor sees any current. The directional diodes are of standard type so they drop 0.7V and we get 1.4V across the Forward or Reverse lamps. Note that the 'Always' lamps are still connected across the inner set of diodes only - if you connect them where the F/R circuits are you will put 2.1V on them The downsides of this circuit (as compared to System 1) is even higher starting volts for the loco and more components and heat loss to fit into the shell. If you can't see the pictures above, here are links to them which may work: System 1 System 2 I've been looking at one of my P2K switchers (P2K use 1.5V bulbs - to the irritation of prospective DCC installers) and traced out the circuit they use. It also has 8 diodes and appears to give a similar end result to my System 2, but with two differences. One is that the motor power has to pass through 4 diodes, which is equivalent to 2.8V, and the other is that I can't see any way to extract a supply for 'Always' lamps. I'm not sure why they have done it the way they have (unless it was just to make the circuit board easier to make) so maybe I've missed something in my circuits. For ratings, the diodes feeding the motor (those shown vertical) only need to handle the supply voltage and motor current, so 50V / 1 Amp should be plenty. The direction diodes need to handle the supply volts and the lamp current - for four 15mA bulbs that's 60mA and you'll struggle to find a diode that won't handle that! Power dissipation is not huge. For a 1 Amp motor current each of the conducting diodes will give off 0.7 Watts, but most HO motors rarely draw half that much, and not for long either, so half-watt diodes would be adequate. The directional light diodes will give off very little heat. Note that if you use a 'PWM' controller type, which may include some 'feedback' controllers, this principle won't work properly. It shouldn't hurt anything, but you won't get constant brightness. The motor diodes may also stop feedback working properly if you have it.
Mike, I understand all to the point of whats happening an where the parts go. Thats all good... My question is, I need to know which system is better for regular DC Cab Control... NOT DCC! And also, what ratings the diodes are an such as you know the bulbs WILL be in sets, of 2 bulbs each. Look at your loco's... They got 2 holes for the head lights, 2 holes for the reverse lights, an one hole for each ditch light, PLUS one hole for each marker light. As you have it listed all bulbs are 1.5 volt DC. BUT being each one of the openings for the headlights will have a bulb in it... So, 2 holes for the headlight gets one bulb per hole, same for the reverse lights. The Marker lights an ditch lights get one bulb per hole. I'm going to use the bulb itself for the light lens! My question is, why would you need a diode to take up voltage from the motor? I don't understand this! I WANT maximum power to the motor but I NEED to lower only the voltage to the lights themself. This is what I don't understand. And depending on what system you think is best for regular DC Cab Control, I need values for the diodes, being I may have to go an buy them, if I don't have them, from Radio Shack. So, I know what I'm going to buy when I go to buy it. And not get the wrong components. This may turn out technical yet! and confusing but once I understand it well...... It will be easy to do then later as I would have a problem understanding it all for doing this same thing to my other loco's....
Also, forgot to mention, in your diagrams, is their a way you can put the values for the diodes beside each one shown ???? This would GREATLY be of help to me.. Once I know which system diagram to use.....
QUOTE "My question is, I need to know which system is better for regular DC Cab Control... NOT DCC!" Sorry my bad, I shoudn't have put the DCC comment in. BOTH these systems are for ordinary systems - neither will work sensibly with DCC. "And also, what ratings the diodes are an such as you know the bulbs WILL be in sets, of 2 bulbs each. Look at your loco's... They got 2 holes for the head lights, 2 holes for the reverse lights, an one hole for each ditch light, PLUS one hole for each marker light. As you have it listed all bulbs are 1.5 volt DC. BUT being each one of the openings for the headlights will have a bulb in it..." "So, 2 holes for the headlight gets one bulb per hole, same for the reverse lights. The Marker lights an ditch lights get one bulb per hole. I'm going to use the bulb itself for the light lens!" The nice thing with this is that the number of bulbs is pretty much irrelevant. In my circuits I have assumed you have 2 headlight + 2 ditchlight bulbs going forward, just 2 headlights going reverse, and 4 marker or other lights on in both directions (Always). You can add or subtract bulbs to those groups as you wish without noticeably affecting the operation. eg. if you want to add 4 step lights to the Always group giving you 8 - just do it. Wire all bulbs in a group in parallel as shown in my diagrams. "My question is, why would you need a diode to take up voltage from the motor? I don't understand this! I WANT maximum power to the motor but I NEED to lower only the voltage to the lights themself. This is what I don't understand." Oh, now you are getting into philosophy. All the systems mentioned in this thread have compromises, and robbing the motor is this one's. However the plus sides are simplicity, cheapness and constant lighting when the loco is moving (and when stopped if you set the controller at the right value). Unless you regularly run your trains with the throttle turned to maximum, you won't have a problem with motor power(Voltage to be precise). Most controllers can deliver more voltage than needed normally, so can just be turned up a tad to compensate. The only time you may see something odd is if you mix these locos with others in the same consist - different starting volts. But you would get that with P2K locos anyway! (Locos using System 2 should work well with P2K engines ) "And depending on what system you think is best for regular DC Cab Control, I need values for the diodes, being I may have to go an buy them, if I don't have them, from Radio Shack. So, I know what I'm going to buy when I go to buy it. And not get the wrong components." I suggest you start with probably the commonest semiconductor on the planet - the humble 1N4000 series diode. My P2K switcher uses 1N4002, but if you have 1N4001, 1N4003 or 1N4004 to hand already they are the same except for the reverse voltage rating which is adequate on all these. Use 8 of these in my Sytem 2 above and see what sort of volts you get on the bulbs. In the unlikely event it's not OK we'll have to find something better, but if it works for P2K .... I'll try and mod the diagrams later. [ 07. September 2003, 09:46: Message edited by: Mike Sheridan ]
Mike, Oh, now you are getting into philosophy. All the systems mentioned in this thread have compromises, and robbing the motor is this one's. However the plus sides are simplicity, cheapness and constant lighting when the loco is moving (and when stopped if you set the controller at the right value). Unless you regularly run your trains with the throttle turned to maximum, you won't have a problem with motor power(Voltage to be precise). Most controllers can deliver more voltage than needed normally, so can just be turned up a tad to compensate. The only time you may see something odd is if you mix these locos with others in the same consist - different starting volts. But you would get that with P2K locos anyway! (Locos using System 2 should work well with P2K engines See thats just it. I run my loco's with LOTS of other ones... that may not get this same treatment an NONE of the others are as slow as the P2K units! This is what I'm worried about. Being I don't have many P2K loco's I need them to run at least near the same speed.... The biggest thought here is the fact that I'm custom building this locomotive! Its a Rail Power Products SD-90MAC-H shell, and frame, that I'm building to be designed like the Athearn DD-40, with dual motors! I'm going to use 2 of the high output Athearn C44-9W motors. With a flywheel between the 2 motors, an a fly wheel on each "truck" end of the 2 motors (3 flywheels total). I'm wanting pulling power an this is how I'm going to get it, plus I'm adding more weight to it as well.... besides the RPP cast frame. Later on, I may remove the 2 Athearn high output motors an replace them with A-Line precision can motors!!!! So you see my possition here???? I don't want it to slow the loco down being the motor voltage has droped.... Is their a way I can run the power to the motor, an then AFTER the motor add the components ??? Being I may run this loco, with say an Athearn AC44CW, or even a C44-9W.... So, this is my reasons for wondering about the motor voltage drop to the motor..... I suggest you start with probably the commonest semiconductor on the planet - the humble 1N4000 series diode. My P2K switcher uses 1N4002, but if you have 1N4001, 1N4003 or 1N4004 to hand already they are the same except for the reverse voltage rating which is adequate on all these. Use 8 of these in my Sytem 2 above and see what sort of volts you get on the bulbs. In the unlikely event it's not OK we'll have to find something better, but if it works for P2K .... The number "1N4000" is that a Radio Shack parts/stock number??? Being I have to get what I need to make this work.... This is why I asked for a ohms/volts/amp value to each diode etc.... That way I can go and look for the proper value to these diodes wether it be a Radio Shack part or some other company part. The nice thing with this is that the number of bulbs is pretty much irrelevant. In my circuits I have assumed you have 2 headlight + 2 ditchlight bulbs going forward, just 2 headlights going reverse, and 4 marker or other lights on in both directions (Always). You can add or subtract bulbs to those groups as you wish without noticeably affecting the operation. eg. if you want to add 4 step lights to the Always group giving you 8 - just do it. Wire all bulbs in a group in parallel as shown in my diagrams. This is good! I may want to add a cab interior light, or even the step lights (I'm not sure on this one yet.) But, I like this idea, it keeps everything simple....
