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Author Topic: 1Hz Timing Circuit Needed...  (Read 3807 times)

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Offline voyager2Topic starter

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1Hz Timing Circuit Needed...
« on: July 16, 2010, 10:11:41 PM »
Hi All,
I've been working on my fish lately, and need a 1Hz or 2Hz timing circuit to test the tail with.
I need it to be simple, no ICs, programing, etc.
I have limited time and components.
I first thought of a RC circuit(Resistor Capacitor circuit)but my experience is limited.
All it has to do is swap the polarity of two wires every second(or half second with 2Hz)
I couldn't find anything on SoR, Google, or Yahoo!.
Please help.

Voyager2
« Last Edit: July 16, 2010, 10:27:08 PM by voyager2 »
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Offline futmacl

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Re: 1Hz Timing Circuit Needed...
« Reply #1 on: July 16, 2010, 10:46:14 PM »
I've been working on my fish lately, and need a 1Hz or 2Hz timing circuit to test the tail with.
All it has to do is swap the polarity of two wires.


If you search for "LED flasher", you will find quite a few 2-transistor circuits around 1-2 Hz - say:

http://talkingelectronics.com/projects/CircuitTricks/images/LedFlasher.gif

That said, a 555 timer configured for 1 Hz (http://sites.google.com/site/uzzors2k/555Tester_schematic-full.jpg) is actually cheaper and simpler - why the aversion to ICs?

Assuming single supply, switching wire polarity for a motor is actually somewhat tricky. At low frequencies, the easiest option is to use a DPDT relay. For reasonably low currents, you could use a miniature DIP relay that costs about $1:

http://www.allelectronics.com/make-a-store/item/RLY-527/5VDC-DPDT-DIP-RELAY/1.html

This is probably cheaper and easier than building a H-bridge (though H-bridge ICs such as FAN8082 aren't too expensive either).

Offline voyager2Topic starter

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Re: 1Hz Timing Circuit Needed...
« Reply #2 on: July 16, 2010, 10:59:13 PM »
Quote
That said, a 555 timer configured for 1 Hz (http://sites.google.com/site/uzzors2k/555Tester_schematic-full.jpg) is actually cheaper and simpler - why the aversion to ICs?

I don't want to wait 2 weeks for ICs and transistors to ship, I need it now!

Does any one know of a good RC circuit.

Parts I have:
ATmega168s x 5
100uF caps rated at 16v x 10
220uF cap rated at 10v x 1
500Kohm pot x 2
1Kohm resistors x 10
LEDs x 40
MOSFET x 1
Bridge Rectifier x 2
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Offline voyager2Topic starter

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Re: 1Hz Timing Circuit Needed...
« Reply #3 on: July 17, 2010, 04:19:38 AM »
I'm going to buy one of these:
http://www.sparkfun.com/commerce/product_info.php?products_id=9285
Should help alot!
« Last Edit: July 17, 2010, 04:53:04 AM by voyager2 »
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Offline amando96

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Re: 1Hz Timing Circuit Needed...
« Reply #4 on: July 17, 2010, 04:54:53 AM »
Get a cheap wristwatch and use the circuitry inside it.
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Offline waltr

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Re: 1Hz Timing Circuit Needed...
« Reply #5 on: July 17, 2010, 08:00:18 AM »
Write a quick piece of code for the Atmega to toogle an output pin.

Offline Soeren

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Re: 1Hz Timing Circuit Needed...
« Reply #6 on: July 17, 2010, 05:13:07 PM »
Hi,

All it has to do is swap the polarity of two wires every second(or half second with 2Hz)
Then a 2 transistor AMV is the simplest solution - transistors can be chosen for the needed current.
Regards,
Søren

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Offline voyager2Topic starter

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Re: 1Hz Timing Circuit Needed...
« Reply #7 on: July 19, 2010, 04:36:32 AM »
Get a cheap wristwatch and use the circuitry inside it.
Wrist-watches are not cheap here in Australia!
Since this is just to test the tail, I don't want to spend $20 on a digital watch.

Write a quick piece of code for the Atmega to toogle an output pin.
I'm to lazy to program, that's what I'll do for the finished product.

Hi,

All it has to do is swap the polarity of two wires every second(or half second with 2Hz)
Then a 2 transistor AMV is the simplest solution - transistors can be chosen for the needed current.

What is a transistor AMV?
I am a total noob...
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Offline Joker94

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Re: 1Hz Timing Circuit Needed...
« Reply #8 on: July 19, 2010, 05:07:55 AM »
well given what you are saying all you need is a double pole double throw switch. it is really easy, and that is really all you sound like you need.

2 bucks from dick smiths

Offline voyager2Topic starter

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Re: 1Hz Timing Circuit Needed...
« Reply #9 on: July 19, 2010, 05:09:57 AM »
well given what you are saying all you need is a double pole double throw switch. it is really easy, and that is really all you sound like you need.

2 bucks from dick smiths

I need it to do do all this by itself, not manually.
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Offline SmAsH

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Re: 1Hz Timing Circuit Needed...
« Reply #10 on: July 19, 2010, 05:13:58 AM »
Dude, watch from the reject shop - $2-4.
Howdy

Offline voyager2Topic starter

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Re: 1Hz Timing Circuit Needed...
« Reply #11 on: July 19, 2010, 05:17:56 AM »
OK I'll try to find one, that is not: massive, barbie printed or pink ::)
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Offline Razor Concepts

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Re: 1Hz Timing Circuit Needed...
« Reply #12 on: July 19, 2010, 05:23:26 AM »
Arduino? Select the arduino pro 8mhz option and you are set. Really easy code

Offline voyager2Topic starter

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Re: 1Hz Timing Circuit Needed...
« Reply #13 on: July 19, 2010, 06:11:12 AM »
I don't have an Arduino, I'm going the squash the $50 robot into it.
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Offline Razor Concepts

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Re: 1Hz Timing Circuit Needed...
« Reply #14 on: July 19, 2010, 07:15:14 AM »
I mean that you have the mega168, so you can run the arduino code on it.

Offline chelmi

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Re: 1Hz Timing Circuit Needed...
« Reply #15 on: July 19, 2010, 10:08:39 AM »

Write a quick piece of code for the Atmega to toogle an output pin.
I'm to lazy to program, that's what I'll do for the finished product.


The time you spent looking for an "easier" solution would have been enough to write the necessary code...

Offline Soeren

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Re: 1Hz Timing Circuit Needed...
« Reply #16 on: July 19, 2010, 04:31:06 PM »
What is a transistor AMV?
I am a total noob...

Apparently at using Google as well ;)
Here's a page on Astable MultiVibrators (AMVs) - read it all, you'll learn something.
AMV page
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline paulstreats

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Re: 1Hz Timing Circuit Needed...
« Reply #17 on: July 19, 2010, 04:40:53 PM »
Quote
I don't want to wait 2 weeks for ICs and transistors to ship, I need it now!

Thats a shame, theres a few real time clock IC's that produce a 1 hertz pulse direct from a single pin (usually used to pulse a second symbol/dot on clock LCD's) aswell as the other useful functions like keeping time and pulsing a pin when a preset alarm is triggered.

Offline futmacl

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Re: 1Hz Timing Circuit Needed...
« Reply #18 on: July 19, 2010, 04:45:33 PM »
Quote
I don't want to wait 2 weeks for ICs and transistors to ship, I need it now!

If you live anywhere near any sort of civilization, it really doesn't take 2 weeks to get two off-the-mill BJTs or a 555 timer.

Also, you really can't avoid stocking these components forever; if you do not have a reasonable library of passive components, transistors, and some of the most popular ICs, you will suffer.

Offline macdad-

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Re: 1Hz Timing Circuit Needed...
« Reply #19 on: July 27, 2010, 12:26:50 PM »
I first thought of a RC circuit(Resistor Capacitor circuit)but my experience is limited....

For future reference:

Formula for RC circuits:

Frequency = 1/(2*pi*R*C)
R - Resistor Value
C - Capacitor Value

Of course you would still need a semiconductor for the oscillation as just a RC circuit by itself is used as a Low/High pass filter which blocks frequencies above or below the Frequency in the above formula all depending upon the wiring of the circuit.

 


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