Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
i would like to make a very simple shift light that detects rpms fron the cig lighter voltage and not the tacho wire.
axis and other comapnies make them. http://mikeegan.stormpages.com/Shift.html
does anyone have a simply circuit ?, i want one led to come on at about 4krpm and one at 6.5k rpm.
i need a simple circuit that simulates a mobile phone making a call, i want to have display board that shows mobile phone accesories that flash when you make a call eg. flashing keypads, batteries etc. i have seen displays at markets.
i have been told that cars can generate a negitive voltage transient upto 400v, therfore led's in cars should always be protected my a diode becuase leds can usually only handle negitive voltages upto 5v. is this correct? and if so what would be a suitable surface mount replacement for a 1n4004...
currently i am using a 1n4004 diode to protect against reversed polarity in a circuit, the circuit only draws 50ma. I would like to replace the 1n4004 with a surface mount diode to save space, what would a suitable replacement be ?
thanks
i am trying to run an led from a car, i obviously need a resistor to do this, at the moment i am using a 470ohm 1/4 watts resitor (this is running it about half it's brightness, this is bright enough), but i want to use a smd resistor. The problem is the LED needs atleast a 1/4 watt 470ohm...
i want a way of storing upto 700 phone numbers on a mobile phone sim card, in the phonebook (nokia phone). i have seen blank sim cards that can store 250 numbers and can have upto 12 different operators, it's like having 12 sim cards on one. I'm thinking if they didn't waste all the space on the...
i need to freeze the 4029 when it outputs from q4, i want to lock it so when it outputs from q4 it freezes so it continues to output from q4. i can jam the 555 timer with a negitive pulse which then freezes the 4029 but to to that i have to use a relay or transistor, but i want to jam it with...
i only need ennough current to run the timer circuit and a very small 5cv relay.
is this circuit how i do it, if so what size should the resistor be ??
the circuit only works when i run it from 2-6 volts, i need it to run from 9v how can i drop the voltage down to around 5 or 6 volts, itried using resistors but it didn't work. cani use zeners or something ??.
i need a circuit so that when power is applied to it the a relay will close after about 10 secs and stay on. It should be a very simple circuit but i have tried 3 circuits now and none have worked.
cir1 = worked perfectly for a led but outputs a maximum of 5v (not enough to drive a relay)...
came across this on the net, i tried this new circuit and it works perfectly, it also explains why the other circuit didn't work
" The following circuit uses two 1N4148 diodes to protect parallel port against higher than +5V signals and also against wrong polarity signals (power on the...
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