Here I will explain how the terminal track is wired, and the basic theory of how the power is supplied and controlled for forward and reversing of the slot cars.
Above is a typical “center-off” terminal track with wire locations marked. When you plug in the 3001 Power Pack, it takes 120 volt (or 240 VAC for export sets) and by means of a “converter”, it changes the AC into DC. The output DC will vary between the older 6.9 VDC and newer 7.9 VDC Power Pack. Both output 2 amps. I used a 6.9 VDC Pack, and as you can see it was outputting a bit over 8 VDC to the rails.
When plugging in the connector, the positive side should be on the right. Older plugs do not show, but newer plugs will have a “+” on one side noting the positive side. If the plug is reversed, the trucks will run backward.
The four wires used on the terminal are white, black, red, and yellow.
So, as shown below, when the plug is inserted, it provides power to the track. The power is supplied to the white and black wires. These are soldered together to provide either power or ground to each wire. The white wire will be on the same side controller, while the black routes to the opposite side controller. Notice a “ground” is connected to the positive side on the bottom ear, more on that in a bit…
The red and yellow wires are connected to the track rails. Notice that there are terminal connectors on each wire to facilitate removal. This allows for the track or controller to be easily replaced.
Above is the center-off controller. The white wire provides “+” voltage to the end of the switch. The black wire provides ground to the middle/top area. As the wheel is turned to forward (to the right) the contact end moves to the left and will touch the left plate and provide “+” voltage to the red wire.
The top of the contact will move to the right, where it will contact the resistor and provide “ground” to the yellow wire.
So, interestingly, basic DC circuit theory usually has a positive + side, and a ground - side. But, in this case, the ground is turned into “negative” voltage. This is done by providing power below ground voltage, or “0”, which then becomes -7.9 VDC, for example.
So in effect, the speed is determined by shunting the negative voltage. I was wrong before when I said the amperage was changed by the resistor. I had forgot there is such a thing as negative voltage and that the terminal uses it.
The output power of the power pack remains constant regardless of speed selected at the track rails. When a truck is put on the track, >then< the voltage is regulated by the resistor, and will show an increase/decrease of voltage on a multimeter at the rails.
My specific controller resistor has around 32 Ohms of resistance, and showed 2.3 VDC just off the park base, and around 6.2 volts at Max. Considering the rail had over 8 volts, there is a lot of resistance in that specific chassis.
Reverse is similar to forward, except then the yellow has positive voltage, and the red wire then becomes negative and regulated by the resistor.
This is a close up to show that there is a sleeve placed on a lamp for a lighted chassis. Probably because that is the positive motor ear on the slot car, and typically they will be ran in forward more than reverse. That is to protect the wire from touching metal and causing a direct short.
The bulb is ambidextrous and doesn’t have a typical positive and ground side, as running in reverse switches power to the bare wire and lights it.
Above is a typical “center-off” terminal track with wire locations marked. When you plug in the 3001 Power Pack, it takes 120 volt (or 240 VAC for export sets) and by means of a “converter”, it changes the AC into DC. The output DC will vary between the older 6.9 VDC and newer 7.9 VDC Power Pack. Both output 2 amps. I used a 6.9 VDC Pack, and as you can see it was outputting a bit over 8 VDC to the rails.
When plugging in the connector, the positive side should be on the right. Older plugs do not show, but newer plugs will have a “+” on one side noting the positive side. If the plug is reversed, the trucks will run backward.
The four wires used on the terminal are white, black, red, and yellow.
So, as shown below, when the plug is inserted, it provides power to the track. The power is supplied to the white and black wires. These are soldered together to provide either power or ground to each wire. The white wire will be on the same side controller, while the black routes to the opposite side controller. Notice a “ground” is connected to the positive side on the bottom ear, more on that in a bit…
The red and yellow wires are connected to the track rails. Notice that there are terminal connectors on each wire to facilitate removal. This allows for the track or controller to be easily replaced.
Above is the center-off controller. The white wire provides “+” voltage to the end of the switch. The black wire provides ground to the middle/top area. As the wheel is turned to forward (to the right) the contact end moves to the left and will touch the left plate and provide “+” voltage to the red wire.
The top of the contact will move to the right, where it will contact the resistor and provide “ground” to the yellow wire.
So, interestingly, basic DC circuit theory usually has a positive + side, and a ground - side. But, in this case, the ground is turned into “negative” voltage. This is done by providing power below ground voltage, or “0”, which then becomes -7.9 VDC, for example.
So in effect, the speed is determined by shunting the negative voltage. I was wrong before when I said the amperage was changed by the resistor. I had forgot there is such a thing as negative voltage and that the terminal uses it.
The output power of the power pack remains constant regardless of speed selected at the track rails. When a truck is put on the track, >then< the voltage is regulated by the resistor, and will show an increase/decrease of voltage on a multimeter at the rails.
My specific controller resistor has around 32 Ohms of resistance, and showed 2.3 VDC just off the park base, and around 6.2 volts at Max. Considering the rail had over 8 volts, there is a lot of resistance in that specific chassis.
Reverse is similar to forward, except then the yellow has positive voltage, and the red wire then becomes negative and regulated by the resistor.
This is a close up to show that there is a sleeve placed on a lamp for a lighted chassis. Probably because that is the positive motor ear on the slot car, and typically they will be ran in forward more than reverse. That is to protect the wire from touching metal and causing a direct short.
The bulb is ambidextrous and doesn’t have a typical positive and ground side, as running in reverse switches power to the bare wire and lights it.
