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In normal suburban driving you pass through so many different speed zones that it can be a nuisance having to switch speed settings. The speed display can also be a distraction. This circuit eliminates the display and the need for speed selection. Each time you exceed a particular speed setting (eg, 40km/h, 50km/h, etc), a piezo buzzer will beep. Speed pulses are fed to the base of Q1 and the resulting waveform at its collector is fed via an RC network to the input of an LM2917 frequency-to-voltage converter, IC1. The resulting voltage is fed to three comparators (IC2d-IC2b) which have the reference voltages at their inverting inputs set by 10-turn trimpots VR1, VR2 & VR3. The output of each comparator is applied via another RC network to the gate of an SCR. The anodes of the three SCRs are commoned connected to the inverting input of the remaining comparator, IC2a. Circuit diagram: Speed Alarm Circuit Diagram Its non-inverting input is set to +2.3V by trimpot VR4. In use, on...

This is a question that many people have currently as robotic cars begin to become more of a reality in the modern world. Whether it's the one being developed by Google or all the other automatic vehicles that are being developed, it's a very exciting time to be alive if you love technology. Still, many people wonder if computers can replace humans as drivers and do a better job. Over at the MIT Technology Review, they've taken a closer look at this problem. Photo credits: Juhan Sonin Chris Urmson - from Google - made the claim earlier this year that Google's auto-driving Prius and Lexus cars are smoother than humans. He made the announcement at a robotics conference this summer in Santa Clara, California. Read More.....

The author gave his partner a radio controlled (RC) model car as a gif t. She found it a lot of fun, but thought that adding realistic lights would be a definite improvement. So the author went back to his shed, plugged in his soldering iron, and set to work equipping the car with realistic indicators, headlights, tail lights and brake lights. Lights Control for Model Cars Circuit Diagram The basic idea was to tap into the signal from the radio control receiver and, with a bit of help from a microcontroller, simulate indicators using flashing yellow LEDs and brake lights using red LEDs. Further red LEDs are used for the tail lights, and white LEDs for the headlights. Connectors JP4 and JP5 (channel 0) are wired in parallel, as are JP6 and JP7 (channel 1), allowing the circuit to be inserted into the servo control cables for the steering and drive motor respectively. The ATtiny45 micro-controller takes power from the radio receiver via diode D1. T1 and T2 buffer the servo signals to pr...