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Simple rotary switch voltage drop unit
I started this project to give me the ability to independently drop the voltage of each lane of the track, this was initially to have my daughter run with me and not come off every corner. I soon found that this was also great for running unmatched cars together for example a Slot it McLaren F1 against a SCX rally car.
This guide shows the parts and method I used in its rough prototype form. I have gone one step further and actually made up a circuit wiper board to replace the resistor in my Parma controller allowing me to use Diodes instead of resistors.
Rotary switch
Parts Used
Switch - http://www.maplin.co.uk/rotary-switches-2417 12 way is the one I have
Diodes - http://www.maplin.co.uk/rectifier-diode-19079 I don't remember which I selected
My track is powered by a digital adjustable DC supply 0-30V 0-3amp. The negative goes direct from the DC supply to the track and the positive goes through the controller. This switch is placed in the positive feed between the controller and the track. This is the configuration of my track. I'm sure the switch could be placed in either wire either side of the controller providing the current flow direction was correct.
The Build
The main thing to remember is that power will only flow one way through a diode, this means all diodes in the switch need to face the same way. It doesn't matter which way they are soldered to the switch.
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The first two pictures show the switch on the cable. The third picture shows it mounted to the circuit board of the controller. Both are acting in exactly the same way and are on the same wire.
The Diode controller
I had the issue of controller resistance not matching car motor resistance, I'm sure we all have this at some point but don't realise what it is.
With resistor controllers like the Parma's you get a different feel with different cars depending on the motors resistance. Hotter/faster motors like lower resistance in the controller 10 -15 ohm and Scaley type motors like higher resistance in the controller like 45-55 or higher and all the others somewhere between. if the resistance in the controller does not match the resistance in the motor you get a strange effect such as the trigger can be pulled 50% before the car moves or the other way round where the car is off the line as soon as the trigger is moved and at full throttle when the trigger is only 50% pulled. That is because these controllers restrict CURRENT to the cars.
The Diode controller I made does not restrict the current, it controls the voltage. Each diode in the line drops around 0.5 - 0.6 volts so as the trigger moves along the wiper it passes through more or less diodes hence dropping more or less voltage. The effect on the cars is far smoother power delivery. Its exactly the same as the rotary switch.
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You can see from the pictures that this still in its rough experimental stages, I will be making much neater versions when I get chance. It really has been great having the smoother control of the Diode wiper, I found I have been using the cars that were previously "uncontrollable" a lot more now, I's like having a load of new cars.
I realise I could have saved myself the bother and bought an all singing all dancing controller but to be honest I really enjoyed learning a little about the electronic of the hobby and It's cost almost nothing to make up these switches and wiper board.
I hope this has been of some help to everyone.
I started this project to give me the ability to independently drop the voltage of each lane of the track, this was initially to have my daughter run with me and not come off every corner. I soon found that this was also great for running unmatched cars together for example a Slot it McLaren F1 against a SCX rally car.
This guide shows the parts and method I used in its rough prototype form. I have gone one step further and actually made up a circuit wiper board to replace the resistor in my Parma controller allowing me to use Diodes instead of resistors.
Rotary switch
Parts Used
Switch - http://www.maplin.co.uk/rotary-switches-2417 12 way is the one I have
Diodes - http://www.maplin.co.uk/rectifier-diode-19079 I don't remember which I selected
My track is powered by a digital adjustable DC supply 0-30V 0-3amp. The negative goes direct from the DC supply to the track and the positive goes through the controller. This switch is placed in the positive feed between the controller and the track. This is the configuration of my track. I'm sure the switch could be placed in either wire either side of the controller providing the current flow direction was correct.
The Build
The main thing to remember is that power will only flow one way through a diode, this means all diodes in the switch need to face the same way. It doesn't matter which way they are soldered to the switch.
The first two pictures show the switch on the cable. The third picture shows it mounted to the circuit board of the controller. Both are acting in exactly the same way and are on the same wire.
The Diode controller
I had the issue of controller resistance not matching car motor resistance, I'm sure we all have this at some point but don't realise what it is.
With resistor controllers like the Parma's you get a different feel with different cars depending on the motors resistance. Hotter/faster motors like lower resistance in the controller 10 -15 ohm and Scaley type motors like higher resistance in the controller like 45-55 or higher and all the others somewhere between. if the resistance in the controller does not match the resistance in the motor you get a strange effect such as the trigger can be pulled 50% before the car moves or the other way round where the car is off the line as soon as the trigger is moved and at full throttle when the trigger is only 50% pulled. That is because these controllers restrict CURRENT to the cars.
The Diode controller I made does not restrict the current, it controls the voltage. Each diode in the line drops around 0.5 - 0.6 volts so as the trigger moves along the wiper it passes through more or less diodes hence dropping more or less voltage. The effect on the cars is far smoother power delivery. Its exactly the same as the rotary switch.
You can see from the pictures that this still in its rough experimental stages, I will be making much neater versions when I get chance. It really has been great having the smoother control of the Diode wiper, I found I have been using the cars that were previously "uncontrollable" a lot more now, I's like having a load of new cars.
I realise I could have saved myself the bother and bought an all singing all dancing controller but to be honest I really enjoyed learning a little about the electronic of the hobby and It's cost almost nothing to make up these switches and wiper board.
I hope this has been of some help to everyone.
