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radek tymecki
Joined: Mar 22, 2009 Posts: 85 Location: PL
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Posted: Thu Apr 04, 2013 11:18 pm Post subject:
simple led chaser problem |
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hi there
i've built a simple led chaser circuit and i dont know why it stops after 10-15 sec... dunno why? anyone can help me?
i've used hef4017 and ipaz7555
more info here
http://www.qrp.pops.net/leds.asp |
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comrade_zero
Joined: Mar 05, 2009 Posts: 66 Location: arizona
Audio files: 4
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Posted: Thu Apr 04, 2013 11:28 pm Post subject:
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Try adding a 100k pull down resistor (to ground) on pin 14 (clk in) on your cd4017. Check the original Baby 10 sequencer article for more help if this doesn't help.
Good luck, hope this helps
c_z |
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radek tymecki
Joined: Mar 22, 2009 Posts: 85 Location: PL
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Posted: Fri Apr 05, 2013 1:01 am Post subject:
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i've connected 100k resistor to pin 14 and G... still stops |
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comrade_zero
Joined: Mar 05, 2009 Posts: 66 Location: arizona
Audio files: 4
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Posted: Fri Apr 05, 2013 3:54 am Post subject:
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It looks like your reset pin is grounded. you have to clock it (high) to reset the counter.
If you google baby10 the schematic will help you out.
cheers,
c_z |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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radek tymecki
Joined: Mar 22, 2009 Posts: 85 Location: PL
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Posted: Fri Apr 05, 2013 6:57 am Post subject:
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pin 13 is grounded. ok i'll connect pin 4 to V+ and see what will happen. |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Fri Apr 05, 2013 8:14 am Post subject:
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comrade_zero wrote: | It looks like your reset pin is grounded. you have to clock it (high) to reset the counter. |
Only if you want less then 10 steps, else you can connect it to GND and it will just loop back after 10 steps.
You can make it run just 1 time. Say you want 8 steps then you connect the 9th output to pin 13 (just as you would normally do with the reset pin)
Add a reset button and it will run 1 time everytime you push it, and hold on step 9. _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube Last edited by PHOBoS on Fri Apr 05, 2013 10:44 am; edited 1 time in total |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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Posted: Fri Apr 05, 2013 10:12 am Post subject:
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you could put an led on the clock, to see if the clock is still running, i would also check both chips. _________________ _Richard_ |
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feggster
Joined: Sep 12, 2011 Posts: 52 Location: uk
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Posted: Sat Apr 06, 2013 7:16 am Post subject:
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could it be from using a 7555 (cmos) chip instead of standard 555 ? |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Sat Apr 06, 2013 7:30 am Post subject:
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feggster wrote: | could it be from using a 7555 (cmos) chip instead of standard 555 ? |
ah, I didn't notice that since I only looked at the schematic itself
but from a link on the page where the schematic comes from I got this
Quote: | If the RESET terminal of a 555 or 556 timer is not going to be used, it is normal practice to connect this input to the supply voltage. If the RESET terminal is left unconnected the operation of the timer will not be affected, however, the RESET of CMOS version of these timers should not be left unconnected as the inputs of these devices are more sensitive and this may cause problems. |
so as I mentioned before, connect pin 4 to V+ that might solve it.
does one of the chips get warm/hot btw ? Last edited by PHOBoS on Sat Apr 06, 2013 7:40 am; edited 1 time in total |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sat Apr 06, 2013 7:36 am Post subject:
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Using a 7555 is not the problem, it should easily work in this circuit.
Also, there is no need for a pull up resistor on clock input. Pin 3 of the 7555 is a totem pole so it drives to ground when low and drives to V+ when high.
The big no-no here (as has been pointed out) is that pin 4 of the 7555 is floating and should be connected to V+.
The note PHOBoS quoted about the reset pin refers to a 555 or 556 - which is a BIPOLAR part not CMOS. CMOS inputs (7555 is a CMOS part) should NEVER be allowed to float. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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radek tymecki
Joined: Mar 22, 2009 Posts: 85 Location: PL
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Posted: Sat Apr 06, 2013 1:27 pm Post subject:
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ok i'll remove 100k res and connect pin4 to V+. then we'll se what will happen |
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radek tymecki
Joined: Mar 22, 2009 Posts: 85 Location: PL
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Posted: Sun Apr 07, 2013 3:25 am Post subject:
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pin4 connected to V+ and circuit still stops |
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stewpye
Joined: Apr 30, 2009 Posts: 49 Location: Brisbane, Australia
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Posted: Sun Apr 07, 2013 7:20 pm Post subject:
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Do you have an led via a resistor on the 555 output so you can see if that is still running? (or check it with an oscilloscope).
Stew. |
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radek tymecki
Joined: Mar 22, 2009 Posts: 85 Location: PL
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Posted: Mon Apr 08, 2013 2:14 pm Post subject:
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i've connected led to pin 3 when circuit stopped. the led was flashing all the time... broken 4017? |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Mon Apr 08, 2013 7:48 pm Post subject:
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have you tried a fresh battery?
Just grasping at straws, but.... |
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radek tymecki
Joined: Mar 22, 2009 Posts: 85 Location: PL
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Posted: Tue Apr 09, 2013 9:35 am Post subject:
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i've exchanged 4017 onto new one and it works fine thanks for help |
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