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Simple digital timer Help needed

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friendchooser

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I need to create a simple digital for a mini basketball field model that I am building.
This digital timer will have 2 digits only, and will display second from 00-59.
Example of a 24 second clock from a real basketball game - attached. Note that i need a 00-59 seconds timer.

What I need is someone that will DESIGN this small circut and will write me a short manual that will help me assemble it here by myself.

- This circut should contain the minim 24-Second-Shot-Clock.jpg24-Second-Shot-Clock.jpgal components needed for that.
- the components will be simple, so it could found in any electric store.

- It should contain two optional versions:
1. a device with an on/off switch. Once the device will turned on, the second will start from 00 regardless to where they were when they shut down.
2. A device with no on/off switch. Once the batteries are loaded, it will start counting from 00.
- It will contain the minimum battery power needed, with preferability to one AA battery.
 

mister_rf

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That’s not a simple project for a beginner. :-D From my own experience need to know in advance what types of circuits you may find, and based on the available circuits to create some schematics. See some possible circuits to be used for:

Version A
1 pc CD4518 + 2 pcs CD4511 + NE555 + 2pcs '7segments LED displays' + resistors/capacitors (also may use 1 pc CD4093 circuit)
Version B
2 pcs CD40192 + 2 pcs CD4511 + NE555 + 2pcs '7segments LED displays' + resistors/capacitors
Also, in practice a more simple solution combining some standard digital counters like the one used for ''step pedometers'' with a simple 1Hz oscillator.
lcd step pedometers - Google Search
For a 1Hz oscillator you may use NE555, BJT transistors, see some examples
1 HZ astable circuit - C
 
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betwixt

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It's an obvious application for a small microcontroller because it can do all the timing in software and only needs a few external components. It would require you to write a very simple program though.
The biggest problem is powering it off a single AA cell. This only gives you 1.5V and 7-segment LEDs typically need 3 - 4V to operate properly.

Brian.
 
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