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    Noisy relay now dead - help ~!

    Hello, My stereo amp (NAD 317) when I turned it on started making a ratcheting up buzzer noise which would last about half a second then 'start up' (some relay would click on and all was well)...  This lasted a few days until this weekend when I was going to have a look at it but today it no...
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    Analog Filter advice required

    Hello, Question simplified: Say I had a 48Hz square wave whose high V value was modulated over time (see the black line in the first attached graphic) and I wanted to extract and output the curve of the modulation as a voltage (the red line)... How would I go about this ? Some thoughts that...
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    Freq Gen Help! - Need input in Hz instead of period...

    Hi, I would like to build an device that provides a %50 cycle 0-5v square wave (easy!) - that has a range of frequencies that can be directly inputted from 100.0 Hz to 10,000.0 Hz (harder!) - I would like the 0.1 increments if possible  ... I've played around with a microcontroller called the...
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    Anti-Static Wrist Straps - use with battery powered cct's ??

    Hi, I have never had problems with zapping components in digital ccts and have used a fair amount of different components that came in the static sensitive device bags... The other day two components arrived in the aforementioned bags and they are worth $32US each. I thought it would be a...
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    Adjustable Voltage Reg LM317, Should it be getting this hot ?

    Hi, I've made the little circuit of resistors around an LM317 adjustable voltage regulator that is specified in its spec sheet (240R bet pin1 and pin2 and a 5k pot bet pin1 and gnd)... When using a 12v lead acid battery as an input and regulating the output down to to just above 7.2 volts...
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    DXF - problem with import into PCB, where are my nets - and what are nodes ?

    Hi, I have gone through the DXF 'getting started with PCB design' .pdf with flying colors and decided it was time to create my own cct and PCB... It was a little more complex but really nothing more in terms of using the application - at least i thought... Once I have compiled the schematic...
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    Comments welcome re. amplification/scaling and offset/bias CCT

    Hi, a few months back I made this cct so I could control the output of an LDR (or phototransistor) to give me an output that would cover a 0~X Volt range (X could be anywhere from 12V down to zero). for instance if the LDR output was 2~4V volts I would minus 2 Volts with the bias single gang...
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    Remote control - all i need is one bit (;

    Hi, A project we are working on at the moment requires us the ability to have control of an operate switch on a remote piece of moving gear. Because the sight lines are so unreliable we cant use IR ... Does any one know of a radio control cct or kit that gives us one or more bits of info...
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    Darlington Phototransistor - can i fudge one from an NPN phototransistor ??

    Hi, I am keen to make the circuit outlined here: http://www.aaroncake.net/circuits/slave.htm it calls for a '2N5777 NPN Darlington Phototransistor' of which I am yet to find a supply of here in NZ - upon looking at the symbol used for the Darlington Phototransistor in the cct diagram in the...
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    Servos - PWM - 555 - how to get *really* low switching Hz and duty cycle

    Hi, I am trying to make a servo driving unit for time-lapse photography on an old 60's 16mm camera 8) - the servo will simply push a mechanical button but it needs adjustability that other systems wont give (like cam-follower DC motor or solenoid) - I have so far managed to get the mechanics...
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