Thoughts on buiding a Lionel whistle activation board/circuit?

Stan, you really know what you're doing. After studying it out, I see you have the transistor drawn correctly and after looking at the capacitor again I realized I didn't have it right either. And you're also right about the resistor being 10K. Once I got the light on it just right I could see it had a brown ring instead of violet.

I agree about getting the cost down too. Getting it done as cheaply as possible is another part of the fun.


PS: I'll see if I can get a pic of the K-line board.

quote:

Originally posted by stan2004:
Please don't pay 45 cents for a 1N4001! I see several at Mouser for 10 cents or less, say, 512-1N4001. I'd like to see your parts cost under $1 on principle...never mind shipping being several times that

You might want to check at DigiKey as well. Similar prices, and they're shipping for small orders is much cheaper than Mouser. I normally wait until I have a significant order to buy from Mouser, since shipping ends up being more than the small order.

BTW, what darlington are you using there?

That transistor has a power tab; it is not a TO-92. Can you read any info from the transistor?

I am confused. You are reverse engineering the Lionel board, but the picture is of the K-Line board you aren't copying? How about a picture of the Lionel board?

quote:

Originally posted by stan2004:
Can you post a photo of the burned up board?

quote:

Originally posted by Dale Manquen:
I am confused. You are reverse engineering the Lionel board, but the picture is of the K-Line board you aren't copying? How about a picture of the Lionel board?

Dale, Stan asked for a pic of the burned up board.

Here's the Lionel Board.

quote:

Originally posted by gunrunnerjohn:
You might want to check at DigiKey as well. Similar prices, and they're shipping for small orders is much cheaper than Mouser.
BTW, what darlington are you using there?

The transistor on the board has the following: G24 MPS A13
As far as I can tell, it's the same Manufacturer PN as the link to the Mouser webpage in the first post.

I'll check with Digi-Key before ordering.

OK, I've gone back through Mouser and Digi-Key and priced out all the parts.
'If' I have the correct parts this time, here is what we have.

Mouser

Darlington TO-92 NPN Transistor $.16

1mF 50V Capacitor $.06

470mF 35V Capacitor $.25

1N4001 Rectifier Diode $.08

75K Resistor $.07

10K Resistor $.05

Sub-total $.67
Est. Shipping $4.95 USPS Commercial Address (Cheapest possible) or $6.95 USPS Residential
Total $5.62
-------------------------------------------------------

Digi-Key

Darlington TO-92 NPN Transistor $.55

1mF 50V Capacitor $.18

470MF 35V Capacitor $.44

1N4001 Recifier Diode $.25

75K Resistor $.08

10K Resistor $.08

Sub-total $1.58
Est. Shipping $2.56 USPS Commercial or Residential Address
Total $4.14

Assuming shipping stays the same, if I only build 1-2 boards Digi-Key is cheaper, and 3 or more Mouser is cheaper.

Sounds about right, I do small orders from Digikey if possible, larger orders I figure who is cheaper.

James, you may find some helpful tips here. The sound activation circuit duplicates Lionel's Sound Activation button.
Sound Activation/Block Protector box
http://www.slsprr.net/features/SoundBlkProtect.htm

I reversed engineered the Whistle relay a few years ago.

1720-X050 R1 Whistle Relay

W1 Red AC input W2 Black AC input
W3 Blue Whistle motor positive W4 White Whistle motor negative off Q1 Collector
C1 10 micro F Q1 Emitter to Base C2 470 micro F decoupler across Red and Negative
D1 4002 Red AC wire to R3 and W3 R1 10K ohm
R2 10K ohm to Q1 Base R3 50 Ohm between D1 to W3
Q1 KSP-13 NPN Darlington Transistor: Emitter on W2, Base on R2, Collector on W4


Here are parts for the

600-8152-050 Diesel Horn Circuit

IC1 MSM 4069RS IZ77S
Q1 2N5172 Q2 CD9014
Q3 CIL 232 C1 470 micro F
C2 10 micro F C3 EL 100K
C4 El 100 473J R1 22K ohm
R2 1K ohm R3 10K ohm
R4 270K ohm R5 10K pot
R6 33K ohm R7 10K pot
R8 33K ohm R9 70K ohm
R10 74K ohm R11 17K ohm


Normally, the fault is the Darlington Transistor fails. They are cheap to replace and also found on many of the early Lionel Reverse units.

Looks like the K-Line replace the transitor with a relay instead.

I don't think the one resistor is 75K. While Lionel used different resistors on different boards, they were matched. 75K and 7K is not match. Try the 10K resistors. G

Looking at the schematic, it's easy to see why the Darlington Transistor (MPS-A13) fails. When an inductive load (real, motor, etc) is switched on/off by a transistor, at the moment the transistor turns the motor off, the inductive load wants the current to be contents and expends its energy trying to do so by creating a spike of voltage. If the voltage is higher than the breakdown rating of the transistor, it's time for a new transistor.

What is normally done is a diode is put in reverse across the motor or relay to limit the voltage to .7V and not kill the transistor.

If you look at the KLine relay board, my guess is the diode on the back side is across the relay coil to protect the transistor.

A simple analysis of how the circuit works is that when AC with an average value of 0 V is on the track the Darlington transistor is in the off state. When the whistle button is pushed, the average value of the AC increases and the Darlington transistor conducts and allows current to flow through the motor.

The motor is obviously a DC motor due to the diode and filter capacitor.

Lad

Thanks for the pointers and tips. I'll probably add a few assorted resistor sizes just to cover my bases. Never know when you might need them in the future.

Gotta admire your pricing analysis!

I'm not sure how much you're interested in the how-it-works aspect of your repair but Lad raises a good point about transistors and motor/relay circuits. Obviously I can't speak to what Lionel or whoever designed this was thinking but the reasoning behind why a protection diode is not needed here is the transistor does not "quickly" switch on/off which is what causes spikes. The combination of the 75K resistor and the 1mf capacitor form a filter that slowly (in electrical time) turns the motor on and off.

Likewise, I see you're going with a polarized 1mf cap (as Lionel did). My concern was the so-called "reverse bias" on a polarized capacitor if the Bell button is pressed. That is, for a polarized cap you want to keep the + lead more positive than the - lead. But, a Bell button is infrequently pressed and certainly not held down. Plus, after you changed from 7.5K to 75K, this lowers any current that flows through the cap by 10x so I guess I have to look the other way.

quote:

Originally posted by stan2004:
Gotta admire your pricing analysis!

I'm not sure how much you're interested in the how-it-works aspect of your repair but Lad raises a good point about transistors and motor/relay circuits. Obviously I can't speak to what Lionel or whoever designed this was thinking but the reasoning behind why a protection diode is not needed here is the transistor does not "quickly" switch on/off which is what causes spikes. The combination of the 75K resistor and the 1mf capacitor form a filter that slowly (in electrical time) turns the motor on and off.

It's all interesting to me. Being a novice I need all the knowledge I can get.

quote:

Likewise, I see you're going with a polarized 1mf cap (as Lionel did). My concern was the so-called "reverse bias" on a polarized capacitor if the Bell button is pressed. That is, for a polarized cap you want to keep the + lead more positive than the - lead. But, a Bell button is infrequently pressed and certainly not held down. Plus, after you changed from 7.5K to 75K, this lowers any current that flows through the cap by 10x so I guess I have to look the other way.

I'm going to guess that Lionel went with the polarized cap for the same reason I did. It's cheapest.