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richard.senior

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  • Electronically Interlocking Radio Buttons (*improved!*)

    I bought a small CNC router/engraver last summer (look up CNC3018 pro). If you make your own pcb's, they are worthwhile. Especially for drilling.

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  • Electronically Interlocking Radio Buttons (*improved!*)

    Yes the capacitor does delay allowing the input to be high when the clock pin is raised. I understand.This blog post of yours was actually far more useful than you might imagine.The art of 74xx digital design is not as well documented on the internet as you might think considering how long it's been around.And in fact, I was surprised even to find out that there were a lot of people on electronics stack exchange that didn't know what was meant by 'radio buttons'.Aside from the stuff I've added to the internet whilst researching this, I think this is one of maybe only three articles on digital radio button design.And of those, this is by far the best.What I like about your design is how efficient it is.

    I can get 5 PCB's made up by a company in China, and shipped half way around the world to the UK for about 40 quid (assuming I save on postage by having several different PCB's made in the same order).This particular PCB excluding postage cost around 2 pounds a board.I find large complicated circuits difficult to breadboard. I make constant mistakes to the point where at the end of the process I don't even know if I got it right.Then when you design the PCB a whole new set of mistakes can creep in.If you just start from a working spice model, and have the board made, you know what to amend, and it saves hours and hours of hard work.I'm fundamentally lazy. When it comes down to it I'd rather throw 50 quid at something than spend a week stripping jumper wires and triple checking my work.Whe…

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    I can get 5 PCB's made up by a company in China, and shipped half way around the world to the UK for about 40 quid (assuming I save on postage by having several different PCB's made in the same order).This particular PCB excluding postage cost around 2 pounds a board.I find large complicated circuits difficult to breadboard. I make constant mistakes to the point where at the end of the process I don't even know if I got it right.Then when you design the PCB a whole new set of mistakes can creep in.If you just start from a working spice model, and have the board made, you know what to amend, and it saves hours and hours of hard work.I'm fundamentally lazy. When it comes down to it I'd rather throw 50 quid at something than spend a week stripping jumper wires and triple checking my work.When it comes to manufacturing defects, the boards get a flying probe test for free, so you know they'll be exactly as you designed them. So you've really only got yourself to blame if they don't work. The quality is just astounding for the price.I actually had this board quoted by a UK manufacturer who was going to charge me 200 pounds for 5 boards..I got 6 of these boards, plus six of another, including posting, tax and import duty for 60 pounds. the cost difference is gut-wrenching really.The worst case I've had so far is I got to revision 4 of one PCB.But that particular PCB was small and costing me about 50p each to have made.I think this one is more or less working with one possible bug in the implementation of the CD4051 audio switching system. What looks at the moment to be down to possibly requiring three pulldown resistors, but I don't know yet.Once again thank you for your help..If you're interested in seeing the finished thing working, I'll post a little video here for you.

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  • Electronically Interlocking Radio Buttons (*improved!*)

    Thank you for your reply.This is actually a project a few months into conception. I've actually designed and had made some PCB's (and populated one, see below)Your comments about keeping things close to the power supply entry points are rather worrying for me because one of my design compromises was to make the board long and thin (to keep down PCB cost, and provide foot room between the switches). I have used a ground and 9V plane and a big smoothing capacitor, but still.. things are spread out somewhat.I'm playing my cards a little close to my chest at the moment because this project, whilst not groundbreaking is relatively unique (as far as I can tell) and might make me a small amount of money in the long run (if I can get it working).However, if after checking the things you've mentio…

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    Thank you for your reply.This is actually a project a few months into conception. I've actually designed and had made some PCB's (and populated one, see below)Your comments about keeping things close to the power supply entry points are rather worrying for me because one of my design compromises was to make the board long and thin (to keep down PCB cost, and provide foot room between the switches). I have used a ground and 9V plane and a big smoothing capacitor, but still.. things are spread out somewhat.I'm playing my cards a little close to my chest at the moment because this project, whilst not groundbreaking is relatively unique (as far as I can tell) and might make me a small amount of money in the long run (if I can get it working).However, if after checking the things you've mentioned (swapping the CD40174 for the 74HC version etc.) I still can't get it to work, and you're still willing to help, I'll share the files with you (including the LTSpice files etc.)Once again thank you, it is greatly appreciated.

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