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Old-bie finally inspired for some DIY fun! Need a point in the right direction.

Speakerdesignguy

Jul 27, 2015
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Hello all kind and benevolent electronics gurus!

I have worked as a bench tech, and went to school for electronics however that was well over a decade ago. I have spent the better part of 20 years designing and building loudspeakers, mastering the understanding of analog filtering, understanding amplification topographies, as well as DAC/ADC workings. While there is a foundation there, I have not been much of a tinkerererrr (?) and my career has led to more of a field service work in refrigeration rather than electronics.

One of my favorite hobbies is an outdoor, worldwide scavenger hunt called Geocaching (www.geocaching.com). I am on a quest to integrate unique electronic circuits and puzzles into the containers which the hunters find. The main challenges of these designs will be the following:

1) Outdoor robostness
2) Low static power consumption
3) Low current while in operation/must run off a 9V batteries at most, multiple smaller cells acceptable.
4) Must be small to fit in hide-able containers.

I am old fashion, and most of what I have dealt with is analog. In many ways - the robustness is hard to beat (IMHO), however to build a logic circuit out of a hand full of gates on a breadboard just seems absurd for these applications. Arduino seems a bit of an overkill so for the more complex ideas I am unsure how to proceed. I will try to contribute as much as I can though it may not be much, how I WILL contribute is by starting threads which showcase the projects as I do them in hopes I can help/inspire others for theirs. I am not looking for things to be designed for me, rather a "try this/look here" approach so I am not randomly spit-balling. Here is the first relative conundrum:

I am looking to make a sort of sequence lock. The pattern can be fixed so it does not require "programming" (there's that silly gate talk again), and the output can be a positive trigger as to "push a button". 4-6 "buttons" is all, and just some patters such as "1-2-5-3-4-6" will fire the trigger. Any ideas where I can start?

Thank you in advance for any help and I look forward to finally getting back into electronics!

Warmest,
SDG
 

AnalogKid

Jun 10, 2015
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Microchip (makers of the PIC microcontrollers) have 8-pin parts that draw a few microamps, plenty low enough for a few months of idle time on a couple of AA or coin cells. There are I/O tricks that can get six buttons into the chip with only one I/O pin. What does "fire the trigger" mean? Flash? Beep?

ak
 

Speakerdesignguy

Jul 27, 2015
6
Joined
Jul 27, 2015
Messages
6
Hi AK,
Thanks a bunch. Talking "firing the trigger" would be activating something like a 555 timer for a shot of time which will either energize a small relay, or light some UV LEDs for 30 seconds to be able to read a hidden message. I have several nebulous ideas it can be used for.
 

AnalogKid

Jun 10, 2015
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There are several things to consider as you ramp up. Outdoor/rugged systems need more robust packaging than required for an office environment, and robust usually means closed/insulated. Granted your project will be extremely low power most of the time, but the heat has to go somewhere. Also, work up a crude power budget. 9 V batteries are convenient and cheap, but low power electronics don't run on 9 V, and even a very efficient converter eats up 10% of your power budget before you start doing anything useful. Go back and forth between battery voltage and component power requirements until you have a battery voltage, then start a power or amp-hour budget for test and programming, sleep mode and time, wake-up operation when found, and the output. Add it all up, multiply by 1.5 for margin, and that sets your battery size.

ak
 

Martaine2005

May 12, 2015
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Hi speakerdesignguy,
I think you should do a 'project resource' for speaker design. Best wood, Area/volume, ports, scoops, driver angles etc etc.
Would be a great addition to the site.

Martin
 

Arouse1973

Adam
Dec 18, 2013
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He is a circuit that might be too simple I don't know. The 4 switches connected to the AND gate are the ones you have to switch in order for the output to go high. The other two are disable switches and if any of these are switched then the output will be off. You can change how many you have if you want to. I left the output as open collector because I wasn't sure what you were driving.
Just an idea.
Adam

SW_AND.PNG
 

Speakerdesignguy

Jul 27, 2015
6
Joined
Jul 27, 2015
Messages
6
Hi speakerdesignguy,
I think you should do a 'project resource' for speaker design. Best wood, Area/volume, ports, scoops, driver angles etc etc.
Would be a great addition to the site.

Martin
Greetings Martin,
I will do so. Loudspeaker design is a funny beast. With a couple of on line calculators and some woodworking skils you can make sound. However if you want to build an audiophile pair of speakers that cost mere pennies it is incredibly complex. I will post a link in resources to a website that is a forum. This forum has stikys for existing designs, an NUMEROUS free resources for a beginner, to expert alike. I have been a member for several years and through get togethers have met many of the amazing members.
 

Speakerdesignguy

Jul 27, 2015
6
Joined
Jul 27, 2015
Messages
6
He is a circuit that might be too simple I don't know. The 4 switches connected to the AND gate are the ones you have to switch in order for the output to go high. The other two are disable switches and if any of these are switched then the output will be off. You can change how many you have if you want to. I left the output as open collector because I wasn't sure what you were driving.
Just an idea.
Adam

Adam,
This is exactly what I was looking for! Thank you so much. I appreciate the work up. I will keep posted of progress, though you many not see anything in the immediate. I am working on two other far simpler containers at the moment I will post anyway once they are complete.

This will likely drive an input for a voice box, at least in its original form, which will give Geocachers the coordinates to the next spot.
 

Martaine2005

May 12, 2015
4,219
Joined
May 12, 2015
Messages
4,219
Greetings Martin,
I will do so. Loudspeaker design is a funny beast. With a couple of on line calculators and some woodworking skils you can make sound. However if you want to build an audiophile pair of speakers that cost mere pennies it is incredibly complex. I will post a link in resources to a website that is a forum. This forum has stikys for existing designs, an NUMEROUS free resources for a beginner, to expert alike. I have been a member for several years and through get togethers have met many of the amazing members.
That would be great thank you. I have been making my own designs for a few year too.
I was a mobile DJ years ago and used to build my own amps and speakers. Never really did understand the speaker design..I made them look very nice and they sounded great. Real grunt from bass bins etc.
But my twin 18's would get shown up by somebody with one 12". So I guess I didn't do too well..:)

Martin
 

Speakerdesignguy

Jul 27, 2015
6
Joined
Jul 27, 2015
Messages
6
That would be great thank you. I have been making my own designs for a few year too.
I was a mobile DJ years ago and used to build my own amps and speakers. Never really did understand the speaker design..I made them look very nice and they sounded great. Real grunt from bass bins etc.
But my twin 18's would get shown up by somebody with one 12". So I guess I didn't do too well..:)

Martin
I have done that many times :) Years ago a made a competition sound system for a car which won. It was two 8's which were tuned acoustically to the curve of the car's acoustic rise below 50 Hz. on 250watts, it hit 141dB Which 20 years ago was hard for 12's let alone 8's. My buddy still has the trophy lol. I'll get the link up tonight.

Adam, thanks again!
 

Martaine2005

May 12, 2015
4,219
Joined
May 12, 2015
Messages
4,219
I have done that many times :) Years ago a made a competition sound system for a car which won. It was two 8's which were tuned acoustically to the curve of the car's acoustic rise below 50 Hz. on 250watts, it hit 141dB Which 20 years ago was hard for 12's let alone 8's. My buddy still has the trophy lol. I'll get the link up tonight.

Adam, thanks again!
Haha, fascinating.
Another good read coming up..

Martin
 
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