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Elec-"tricks" frighten me!

Hi all

I'm a mechanical engineer. I live in South Africa and am employed as an aeronautical engineer. I have recently developed an interest in electronics and power electric/eletronic systems.

I am also a musician. I play the piano and (surprise, surprise) guitar. One of my hobbies is to develop an effects board, since no one effects board I can buy gives me all the featrues I want - I would even need 6 different compact pedals to give me only all the possible distortion and overdrive sounds I want, while all of these can be built into one pedal.

Although I am a mechanical engineer, part of our curriculum focussed on electric machines and some analogue and digital systems (transistors as amps, transistors as switches, differential amplifier, non-inverting amp, inverting amp, binary twos-complement calculations etc.) However, all this theory seems to help me zilch at the moment, so I'm hoping to get some practical advice. I am especially interested in three-phase induction machines and variable speed control of these in motor and generator mode. But I can't even make a bar graph voltmeter! Clearly there are things to consider when ordering electronic components that we never learned...

Looking forward to your company!


Well-Known Member
Most Helpful Member
As one of your interests is audio and you don't have a Bar Graph meter, a LM3915 IC and LED display could be a useful starting project.

You can get datasheets for most devices from www.datasheetarchive.com
Last edited:


Well-Known Member
Most Helpful Member
Hi and welcome to the forums. Great place here with quite the collection of people spanning the globe.

As one of your interests is audio and you don't have a Bar Graph meter, a LM3915 IC and LED display could be a useful starting project.
You don't say?

Actually the bar graph volt meter is not hobby-related, it's work-related: I intend to use it as fuel level indicator, which runs off 12V, and has a signal of 0-5V. I use two LM3914 drivers with a 20LED bar. I've followed the instructions, but it's not working. Yes, I've tested the resistors, LEDs, caps and breadboard, and they're all working. No way to check the driver, as far as I know. I know that there are many threads dedicated to the LM3914 on this forum, but to find the time to read through all of them... On the other hand, I don't want to NOT use the search function, and be punished for it either.

Who knew that someone who knows very little about electronics, just happens to be the one who knows the most about it in the whole company...

I'll look into datasheets, thanks a lot.

Reading this back, I sound really unappreciative. Sorry about that, I'm actually really grateful to you, ericgibbs.


A little tip, when searching the forums use google site:www.electro-tech-online.com LM3915 as the forums search function is..umm.. a little lacking. Welcome aboard. I also play guitar and have built a couple of very primitive overdrive pedals, while interesting it hasn't pried me away from my Boss GT8!

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