Various Circuits

This circuit has been designed to alert the vehicle driver that he/she has reached the maximum fixed speed limit (i.e. in a motorway). It eliminates the necessity of looking at the tachometer and to be distracted from driving. There is a strict relation between engine's RPM and vehicle speed, so this device controls RPM, starting to beep and flashing a LED once per second, when maximum fixed speed is reached. Its outstanding feature lies in the fact that no connection is required from circuit to engine.

This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can immobilize the bike, flash the lights etc. Ron has used my Asymmetric Timer as the basis for his design.

These are two - easy to build - relay-based alarms. You can use them to protect your motorcycle - but they have many more applications. If you use relays with 6-volt coils - they'll protect your "Classic Bike". Both alarms are very small. The completed boards occupy about half a cubic-inch - 8 cc. The standby current is zero - so they won't drain your battery.

This document is an introduction to the Wideband Fuel Mixture Display (FMD). We modified the original Silicon Chip Fuel Mixture Display (that used a narrowband sensor) for use as a display for the DIY-WB wideband oxygen sensor controller. After first publishing how to modify the Jaycar KC-5300, we got Jaycar to make up the kits for us and we called them the TE-5300 display. These units were quite successful but we wanted them to be easier to build, so we created the improved TE-5301 display.

The alarm is "set" by opening Sw1. It can be any small 1-amp single-pole change-over switch - but for added security you could use a key-switch. Once Sw1 is opened you have about 10 to 15 seconds to get out of the vehicle and close the door behind you. When you return and open the door the buzzer will sound. You have 10 to 15 seconds to move Sw1 to the "off" position. If you fail to do so, the siren will sound. The output to the siren is intermittent - it switches on and off. The speed at which it switches on and off is set by C6 and R10. While any trigger-switch remains closed, the siren will continue to sound.

Correctly adjusted, the voltage on the pot wiper is slightly less than half D+ (appx. 0.47*D+) and Q1 will conduct if (D+)-(Vp)>6.2+0.7+0.7, or 0.53*(D+) > 7.6V, (D+) > 14.3V. If D+ is lower than 13.7V, Q1 will not conduct, Q2 will get driven via R5, and Q3 will conduct. Df will carry a voltage. When D+ rises, Q1 will start conducting, Q2 will get pinched gradually, and so will Q3. Voltage on Df will drop.

This little circuit uses a LM317 variable voltage regulator to adjust the input voltage down to +9 volt, or whatever else you need. Just a solid basic circuit without bells and whistles. You can do with a 10µF capacitor for C1 if your battery is close to this circuit. If it is located more than 3 feet increase the value to 100µF or above. Without a coolrib it can easily handle 500mA. If you need more, or the maximum current (1.5A), then a good coolrib is required. It can even provide up to 2 amps with a good coolrib and a fan.

To get a more precise output voltage, replace zener diode Z1 with 10V and R1 with a 1Kilo ohm potentiometer. A Coolrib for Q1 is optional but highly recommended. You can replace Q1 for a more robust type to get more output amps depending on your requirements. Simple circuit to power your 9 volt cassette recorder and other stuff.

Here is a picture of the faceplate that holds the LED bargraphs for air/fuel and pulse width as well as the pot to control the fuel mixture above 7psi boost. The switch allows either the primary or secondary injector pulse to be monitored. The faceplate is made of polished aluminum. The air/fuel (O2) monitor, pulse width monitor, and fuel controller are all on one printed circuit board.

There has been a great deal of interest on the Team FC3S list in a cheaper (and if possible, superior) alternative to the expensive FCD's offered commercially. This is understandable given that no modification to the Turbo II that raises the possible boost pressures can be attempted without an FCD. This article presents a simple FCD circuit that can be built by anyone with moderate electronics assembly expertise. In addition, the article covers the reasons why an FCD is needed, why this FCD is superior to other FCD designs, and the theory of operation. By the time you are done reading this article, you will hopefully understand a little more about how your TII works, and a little electronics as well.

This circuit provides up to 20V output from a regular 13.2V automotive battery, to enable constant current charging of nicad battery packs up to 15 cells at 1.2V (18V total). IC1 is a Linear, Audio Power Amp (10W) and was orginally designed for car radios by Toshiba. Several replacement types can be used, like the ECG1288, NTE1288 and other substitutes will work fine. In this circuit, with S1 set in the 'boost' position, IC1 is used to form a squarewave oscillator, and by coupling this square wave to the 13.2V battery supply via D1 and D2 to obtain over 20 vdc. If this is not needed, S1 is left open (normal).

This charger will quickly and easily charge most any lead acid battery. The charger delivers full current until the current drawn by the battery falls to 150 mA. At this time, a lower voltage is applied to finish off and keep from over charging. When the battery is fully charged, the circuit switches off and lights a LED, telling you that the cycle has finished.

This circuit automatically rolls up a car’s electric windows when it rains. The windows are rolled up one at a time while the system monitors the window motor current. When the motor stalls, the system moves to the next window and shuts off it’s the last window.

An unwanted AM car radio plus three transistors is your key to hours of listening enjoyment with this simple receiver. Covering 3.5 to 7.5 megahertz in four bands, it allows reception of radio amateurs, short wave broadcasters, time signals and much more. Its sensitive, stable and simple to build. Look below for the story of the Canning Receiver, first constructed in 1994.

This converter allows an ordinary AM car radio to receive 15.42 MHz (WRNO). A famous talk show is transmitted by this station. The unit should be constructed in a metal box with antenna connectors compatible with the car radio. The converter includes a relay which automatically bypasses the converter when power is removed. A single power wire comes out of the converter box and goes to a power switch located in a convenient spot. (The unit is connected to ground through the coax.) Make sure to keep the leads short and use ground-plane construction. The circuit is not so fussy that a beginner should fear to proceed but it is more challanging than many projects. The performance is quite good and well worth a little effort.

This circuit can become unstable if the layout is poor. Construct the circuit on a piece of copper-clad circuit board material and keep the leads short. The 22 pF input capacitor should have short leads so mount this input near the input connector or use a short piece of coax cable with the shield connected to the copper board.

Anyone performing their own automobile tune-ups knows how important it is to know your engines speed. With this tachometer, you can measure your engines speed without any connections or annoying timing lights.

The intermittent wiper circuit shown above causes the auto's windshield wipers to wipe once every several seconds instead of constantly wiping. The circuit may be added to older cars to provide the intermittent function or it may be used to replace broken wiper circuits in modern cars. The delay is continuously adjustable with the potentiometer but switch selected fixed resistors may also be used, if desired.

Acontinuously working wiper in a car may prove to be a nuisance, especially when it is not raining heavily. By using the circuit described here one can vary sweeping rate of the wiper from once a second to once in ten seconds.

A Very Simple circuit and some Variations. Play with it. All parts are cheap and should be easily obtained. None are very critical.