Hey guys, as some of you guys have heard, I got a 2026. I long to hear the nice air whistle, but my trusty R tranny does not have a whistle rectifier. Could anybody tell me how to make one with parts around the house?
Jerry
Go to Radio Shack and get yourself the following
276-1396 Perf Board
276-1661 Diodes
270-1806 Project box
275-248 Relay
271-131 Resistor
275-1556 Pushbutton
Here’s the schematic
Let me know if you have any questions.
I think he got one with the 2026, he just needs a controller to make it work.
I have a question. If you turn the diodes around, does that make a bell controller?
Gosh durn you, Jerry, how dare you suggest an easy solution when it could be something very complicated [:)].
Your posting got me to thinking that Lionel made something along those same lines. I pulled out my service manual, and you have the basic concept right, but need to make a few slight changes. The battery needs to be put in series with the transformer. This means that it needs to be connected via a single pole double throw momentary switch, and not just a simple push button switch.
I’ll get you an updated schematic in a few minutes
Ben, I just picked up my manual too. Saw that whistle controller.
This is what I have concludedon what should I do after seeing the wiring diagram…
Here is how to make a combined bell and whistle controller with a single D cell:
Connect the common terminal of an SPDT switch to the transformer terminal that would normally go to the center rail of the track. Connect the common terminal of another SPDT switch to the center rail. Connect the normally closed terminals of both switches together and to one terminal of the D cell. Connect the normally open terminals of both switches together and to the other terminal of the D cell. For best results, use pushbutton switches with a snap action.
That’s it exactly, Jerry.
As Bob said, though, make sure you get a good button. Also make sure it can handle plenty of power, as it may be required to on your layout.
As a matter of fact, probably the best solution would be to use pushbutton #275-1556 and relay #274-248 as I listed above. The relay has a 10 amp contacts, which are plenty large for use with trains. It also has a 12 volt DC coil, which can be powered via an inexpensive, low current diode and track power, or a bank of a couple of batteries. The 12 volt coil should trip at about 7 volts.
I have spent quite a while both in the store and online looking, and I have yet to find an apropriate single pole, double throw momentary switch of any sort at Radio Shack that can handle the needs of a railroader.
Is this what we are looking for?
Lionel Part # 6-5906. I have an R transformer and use this part. I believe it was around $15.
Jerry,
Although that would work, notice that the contacts are rated for 3 amps. Your R transfomer is easily capable of putting out 5 amps, and a 2026 with a decent load can pull about 2 1/2, not counting cabooses, etc. If you use that, it would be a good idea to buy a couple of them and have spares in case one is damaged.
Mouser has some 10-ampere switches, their part numbers 633-S305 and 633-S305T.
Gentlemen, the circuit with the battery never did work very well and can be quite dangerous. If you try this circuit NEVER use an Alkaline battery; nasty things can happen. This circuit was designed as a quick method to activate the old whistle relay and the battery did not last very long.
I wonder whether putting a super capacitor around the cell wouldn’t make a big difference to its health. At 60 hertz, 1 farad has an impedance of less than 3 milliohms. With a 3-volt working-voltage rating, you could also use two cells, for more reliable operation.
If you were to use a super cap as an AC bypass for the battery, you would have to use two of them in series, with the negative leads connected to make this a non-polarized capacitor for an AC application. Otherwise the capacitor will blow up from being reverse polarized.
Regards,
Roy
The ac component across a 1-farad capacitor would be only 75 millivolts peak-to-peak at 10 amperes, out of a 1.5-volt dc bias from the battery.
Using RMS current, agreed (asumming Z=1/(j2 x pi x f x C).
For further discussion, polarized electrolytic capacitors tend to look like a diode when reverse biased, which means the cap (ignoring the parallel battery at this point - I am still sorting that out in my mind) would possibly see a very large reverse current each half cycle (vs proper polarity charging, time constant). When the voltage is reversed on an electrolytic, the oxides break down and current flows freely, overheating the electrolyte. Over time (may be in seconds up to a year) this reverse current heating is destructive to the capacitor and at these voltages and currents could be quite spectacular (I have witnessed flames that shoot out several inches). In the schematic shown above, it seems to me that 50% of the time, the capacitor is reverse biased and significant current flows.
As pointed out above - alkaline batteries when reversed biased also overheat and blow out the electrolyte. As with the capacitor the battery also tends to look like a diode to the AC waveform. Obviously in this application, if the whistle blasts are short, the battery will likely not overheat, but will prematurely fail as described.
BTW - there are some who say bipolar electrolytics are not suitable for steady state AC applications.
Regards,
Roy
The capacitor and the D cell are both always biased to a voltage close to the cell voltage, never reversed. The 75 millivolts is much like the ripple on a power-supply filter capacitor. Here are specifications on some super capacitors:
http://info.hobbyengineering.com/specs/PowerStorA_Specs.pdf
The equivalent series resistance is only 90 milliohms for the 1-farad part. A Duracell MN1300 D cell has an esr of 150 milliohms, which means that most of the ac current will flow in the capacitor. The cell resistance can also be enhanced by adding external series resistance to further confine the ac current to the capacitor if that is thought to be a problem.
Bob,
I understand and do not fundamentally disagree with what you are saying. This is interesting, but I admit that I am not totally convinced. Your analysis assumes the battery sufficiently controls (and without failing) what is happening across the capacitor and that is where I have some doubts. The other factor here is 2 - 5 amps into the capacitor even at 50% duty cycle is more than enough to break down the capacitor and apparently the battery too.
This argument depends on what the equivalent resistance of the capacitor is when reverse biased, a characteristic I doubt is documented. In a power DC circuit (say just a few amps), if the capacitor is installed backwards, it usually blows almost instantly (at most within a minute or two), like when a semiconductor punches through.
Regardless, as with many proper power supply designs, I would suggest anyone trying this to install the capacitor in a project box or something to ensure if it blows the capacitor case does not become a dangerous projectile.
Regards,
Roy
The capacitor voltage varies at most between 1.442 and 1.538 volts, that is, the cell voltage of 1.5 volts minus and plus the peak voltage as it charges and discharges. If the cell’s conductance is significant, that only reduces the voltage excursions. So I can’t see any reason to expect the capacitor to be reverse biased. You could always put a substantial diode across it, anyway.
I use a different approach. Get 12 6 amp rectifier diodes,2 European style barrier strips,and 2 push button swiches all available at Radio Shack. Mount the diodes so you have an array 6 in each direction… Jump wires accross the array at both ends. Put this assembly in line between the hot wire and the track. Wire push buttons so each one jumps 5 of one side of the diode array. One button will acivate the bell and the other will activate the whistle. Since each diode drops the current about .6 volts,this hookup would alter a ZWs output from 6-20 volts to 3-17 volts AC allowing smother starts to modern engines. Activating the bell or whistle would give you about 1.5 extra volts to the track to compensate for sound activation. For Postwar tenders you can make the diode array longer giving more compensation so the train doesnt slow down when you activate the whistle. The diode array described is good for 120 watts to the track,very ample in most cases. If you need more capacity you can simply double the Diodes. Use 16 gauge wire or heavier. No soldering is required as the diodes mount easily in the strips.
Dale Hz