This circuit slows the speed of a conventional proportional servo.It regulates the time required for full servo rotation from 1 to 10 seconds without any reduction in the servo’s torque, and every servo position is possible (proportional). source

This circuit works using anything that can transmit serial data and monitor a CTS signal.The controller is a PIC16F84  that uses two lines for serial control. One for serial input and one for DTR/CTS (pin 8 is CTS on a 9 pin connector if you are hooking to a PC). It will take back-to-back updates and doesn’t have jitter.source

Here is one way to combine the best of both worlds and make a normally autonomous Boe-Bot remote controlled – complete with joystick rumble feedback for sensor detections.The toughest part of this project is building the mechanical/electrical interface. You can solve the connector problem by buying a $10 PlayStation extension cable and carefully cutting the socket from one end of it. With a few resistors and a transistor the circuit will be complete and will protect the BASIC Stamp® microcontroller from any dangerous game controller induced electrical noise.source

This is a simple display controller. It can be controlled with a small microcontroller, such as MCS51, 68HC11, Z80, AVR and others.However, it is not suitable for practical use because the microcontroller is occupied in synthesizing video signal, it cannot process any other operation. The CPLD used for main controller is XC95108(PLCC). It has 108 macrocells and 69 I/O port(some have gloval function), so that it is just suitable for this project.Most function is integrated into the XC95108, therefore, number of parts and wires could be reduced. The CRTC block is counter array to generate display timing. The timing controller block is the main logic to arbitrate between host access and display access to the video buffer.source

Using a CMOS version of the 555 timer, this circuit can be used to control the speed of a motor by adjusting the duty cycle of the pulses sent to the motor. source