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Creating a new circuit for a beginner

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hoganc

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Hi there,

I would like to create a small gadget for my desk in work? However, I have no idea where to start. Running from some batteries, I want a some leds to light up the more I turn a dial and then every fifth led I want a bell to ring. on the final led I want a pre-recorded sound to play. Ideally I would like each led to light up on its own.

I have no idea what components I will need or if this is even possible, I have a picture in my head as to what it should look like, attached. Can anyone point me in the right direction.

Thanks
Conan
 

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Do you want to build it yourself. If you had a diagram(schematic) could you read it a built it yourself, or do you want someone else to build it for you? I can help you with the design, or even help you with the construction.
 
Hi there,

I would like to try build it myself, calm me glutton for punishment but I thought it might be a bit of fun. I have seen some basic schematics and understand ohms law. I have never built a circuit though. However, I don't know what some of the components are. I.e. Would I use a variable resistor potentiometer as the dial or something else?
Also what would I use as the recorded voice bit? I have seen many things such as kids toy keyrings with voice on them for a £1 or less but don't know what's in them. Any help would be grateful. Thanks for taking the time to respond.
C
 
Hi there,

I would like to try build it myself, calm me glutton for punishment but I thought it might be a bit of fun. I have seen some basic schematics and understand ohms law. I have never built a circuit though. However, I don't know what some of the components are. I.e. Would I use a variable resistor potentiometer as the dial or something else?
Also what would I use as the recorded voice bit? I have seen many things such as kids toy keyrings with voice on them for a £1 or less but don't know what's in them. Any help would be grateful. Thanks for taking the time to respond.
C
Welcome to this forum. First you are going to either need a microprocessor and then get it programed, or use some integrated circuit counters. I can easily help you design the circuit with integrated circuits. There are members of this forum that are good at doing a project like this with microprocessors. I can guide you through with IC's. Your location will be a great help to anyone.
 
One reasonably easy approach would be to cascade three LM3914's; you'd only need 2 & 1/2 of them, but that and a pot would pretty much take care of the 25 progressive LEDs.
 
Thanks all for the assistance - LM3914 v a microprocessor

Which is easiest?

The LM3914 or the Microprocessor? Also, where do i start with a diagram?

thanks

Hogey
 
It depends on your definition of easy. An LM3914 would most likely be quicker to build and for someone with little to know electronics knowlege, this is the one that I would recomend. The catch is that it will be tricky to get the alarm to sound at the specific LED and the prerecorded message is another signifigant challange. The microprocessor or microcontroller could be quicker to build with the external components but would take longer to program. If you have someone helping you with the process you can try to go with the microcontroller. It would be easier to have the microcontroller sound on the LEDs since it would be the one in control, and it would be signifigantly easier to have it play the prerecorded sound since most audio recording chips opperate off of the 5V logic range. If it is a more simple sound, the microcontroller itself would be able to play the sound.
 
Thanks Dragon Tamer,

Can you tell me the name of the micro controller/ processor that you would recommend? This is only for a bit of a laugh so I don't want to spend big bucks on it.. I can even ditch the pre-recorded sound at the top if it would make things easier?

The LM3914 looks like it might be the easiest looking at the data sheet but I dont know anything about the alternative i.e. what language and system it would have to be programmed in.
could you advise?

Thanks
 
Do you want to build it yourself. If you had a diagram(schematic) could you read it a built it yourself, or do you want someone else to build it for you? I can help you with the design, or even help you with the construction.

if someone else were to build it for me how much do you reckon it would cost?
Thanks
 
if someone else were to build it for me how much do you reckon it would cost?
Thanks
The cost depends upon a number of factors. Such as component count, labor,shipping costs. Yes as sgtwook said LM3914's would work. As dragon tamer mentioned if may be tricky to get the alarm to sound at the right LED. If a opto coupler is connected in series with the appropiate LED that would solve the alarm sounding problem.
I think I could do it with 3ea CD4017 counters,a nand gate clock and a ISD recorder chip for the sound.
 
So looking at the bits that works out at about $10 give or take but wouldn't you need a speaker as well with some resistors?
 
13 hours to create a small circuit like that? Really? So what your saying is about a day and a half (time) and the cost of materials is buttons- I would like to build it myself.. probably take me four days! I have no idea how to program the ISD Chip either?
its all part of a valuable learning experience... I work with lots of electrical engineers so this is a little bit of a laugh and to see if I can actually, plug some bits into a board...
 
...and with LM3914s it would be easy to add some OR logic to play a sound when LED 5,10,15...is on.
For a cheap sound generator would the innards of a musical birthday card do? (provided, of course, you can tolerate repeated playing of the same jingle!). Or small buzzers are available cheaply.
 
Hi there, yeah the innards of a card would be great how would the or gates work? It's ages since I used logic gates I'll have to look them up.
Also if I connect three lm3914s up to one pot how much power/ volts will I need. (I'm probably asking the wrong question) given u have to split the power three ways?
Thanks
 
yeah the innards of a card would be great
I would use the RS kit. The card volume will be vary low.

how would the or gates work?
You just use diodes on the outputs of the LM3914 chips where you what the beeper to work.

how much power/ volts will I need
If you use a 9 volt supply your voltage divider for the pot and chips would have 3 volts per chip and .3 volts per LED.
 
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if someone else were to build it for me how much do you reckon it would cost?
Thanks

I imagine some members here would be willing to make it for free. They would only require you to pay for parts (like a PIC16F for around $2 and various discrete parts) and shipping of the final product.
I, for one, wouldn't mind taking on a small project... ;)

Der Strom
 
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