Model Railroad Group SCR Throttle

It was designed for use on a The London Model Railroad Group's large O scale layout located at London, Ontario, Canada. The prime requirements for the club throttles were that they be rugged, reliable and produce as little heat as possible. Throttles of this type have been in service at the club since 1987 with excellent results. The throttle will deliver 5 amps continuously and up to 18 volts DC. See Notes. More: The Programmable Unijunction Transistor used to trigger the SCR is the key to this design as it ensures that the SCR fires on every cycle of the fullwave DC. This gives a very efficient operation with low voltage loss and very little heat generated.

The electronic circuit described is a robust and efficient throttle design intended for model railroading applications, specifically tailored for a large O scale layout. The circuit is engineered to deliver a continuous current of 5 amps and a maximum voltage of 18 volts DC. This capability is essential for ensuring that the model trains can operate smoothly and reliably under varying load conditions.

At the core of this design is a Programmable Unijunction Transistor (PUT) that plays a critical role in triggering a Silicon Controlled Rectifier (SCR). The PUT is utilized due to its ability to generate a precise timing pulse that ensures the SCR is activated at the appropriate moment in each cycle of the full-wave DC supply. This method of operation not only enhances the efficiency of the circuit but also minimizes voltage drop across the SCR, leading to reduced power loss and heat generation.

The choice of components and the circuit topology are aimed at achieving high durability and reliability. The ruggedness of the design is crucial for its application in a club environment where multiple users may operate the throttles simultaneously. Continuous operation since 1987 demonstrates the effectiveness of the design and its components in meeting the demands of model railroad enthusiasts.

In summary, this throttle design exemplifies a well-engineered solution for model railway applications, combining efficiency, reliability, and minimal thermal output, making it suitable for long-term use in a communal setting.It was designed for use on a "The London Model Railroad Group`s" large O scale layout located at London, Ontario, Canada. The prime requirements for the club throttles were that they be rugged, reliable and produce as little heat as possible.

Throttles of this type have been in service at the club since 1987 with excellent results. The throttle will deliver 5 amps continuously and up to 18 volts DC. See Notes. The Programmable Unijunction Transistor used to trigger the SCR is the key to this design as it ensures that the SCR fires on every cycle of the fullwave DC. This gives a very efficient operation with low voltage loss and very little heat generated. Pleas 🔗 External reference