TL431 IC for low voltage LED flasher
Conundrum, Mon Jul 17 2006, 10:29PMHi all.
Built a 4 level 24V voltmeter using these chips..
Interestingly, this chip can sense 1.25V, above which it sharply switches on in much the same way as the 1381.
Wonder if its possible to build an LED flasher using this, perhaps using another transistor?
Might work well at low currents?
-A
Re: TL431 IC for low voltage LED flasher
Electroholic, Tue Jul 18 2006, 02:02AM
like a charge and dump oscillator?
Electroholic, Tue Jul 18 2006, 02:02AM
like a charge and dump oscillator?
Re: TL431 IC for low voltage LED flasher
Conundrum, Wed Jul 19 2006, 06:12PM
Yeah, basically. Its 2.5V but the same principle applies.
-A
Conundrum, Wed Jul 19 2006, 06:12PM
Yeah, basically. Its 2.5V but the same principle applies.
-A
Re: TL431 IC for low voltage LED flasher
Steve Conner, Wed Jul 19 2006, 08:35PM
I don't know. The TL431 just conducts like a zener diode. For a charge and dump oscillator, you want something that fires and latches on like a SCR. (anyone remember unijunction transistors?)
Steve Conner, Wed Jul 19 2006, 08:35PM
I don't know. The TL431 just conducts like a zener diode. For a charge and dump oscillator, you want something that fires and latches on like a SCR. (anyone remember unijunction transistors?)
Re: TL431 IC for low voltage LED flasher
Electroholic, Thu Jul 20 2006, 05:31AM
I think there is a circuit for the 1381, they used it in BEAM robotics. Solar powered, charge and dump.
Electroholic, Thu Jul 20 2006, 05:31AM
I think there is a circuit for the 1381, they used it in BEAM robotics. Solar powered, charge and dump.
Re: TL431 IC for low voltage LED flasher
Marko, Thu Jul 20 2006, 01:35PM
I just happen to have some here I ordered together with 2950 low drop regulators, wich I wanted to implement for voltage regulation on 4046 chip.
To make a relaxation oscillator you need a component with negative resistance region, like diac, UJT's, SCR (in self-triggering circuit), neon bulbs and spark gaps, etc.
(I think there are some interesting oscillators based on neon bulbs on bjorn's site)
Zener diodes and 431 regulators (wich are actually just something lke adjustable zeners) pwn no negative resistance and they will just 'conduct' once enough voltage is applied, mantaining constant voltage drop on themselves.
Since 431 is adjustable, feedback pin could *maybe* be used to make some kind of negative feedback/relaxation oscillator of sorts, but I'm not quite sure how would it look in reality. I need to dig around a bit more..
Marko, Thu Jul 20 2006, 01:35PM
I just happen to have some here I ordered together with 2950 low drop regulators, wich I wanted to implement for voltage regulation on 4046 chip.
To make a relaxation oscillator you need a component with negative resistance region, like diac, UJT's, SCR (in self-triggering circuit), neon bulbs and spark gaps, etc.
(I think there are some interesting oscillators based on neon bulbs on bjorn's site)
Zener diodes and 431 regulators (wich are actually just something lke adjustable zeners) pwn no negative resistance and they will just 'conduct' once enough voltage is applied, mantaining constant voltage drop on themselves.
Since 431 is adjustable, feedback pin could *maybe* be used to make some kind of negative feedback/relaxation oscillator of sorts, but I'm not quite sure how would it look in reality. I need to dig around a bit more..
Re: TL431 IC for low voltage LED flasher
benbradley, Fri Jul 21 2006, 03:06AM
<i>Since 431 is adjustable, feedback pin could *maybe* be used to make some kind of negative feedback/relaxation oscillator of sorts, but I'm not quite sure how would it look in reality. I need to dig around a bit more..</i>
Like "name that tune" I can draw an LED flasher/oscillator circuit with a 431, three resistors and one capacitor (and of course the LED and a power source). With an r-c network in its feedback path, a 431 can't help but oscillate. Calculating frequency and adjusting on/off ratio will require a little more thought and calculation, but shouldn't be a big deal.
benbradley, Fri Jul 21 2006, 03:06AM
<i>Since 431 is adjustable, feedback pin could *maybe* be used to make some kind of negative feedback/relaxation oscillator of sorts, but I'm not quite sure how would it look in reality. I need to dig around a bit more..</i>
Like "name that tune" I can draw an LED flasher/oscillator circuit with a 431, three resistors and one capacitor (and of course the LED and a power source). With an r-c network in its feedback path, a 431 can't help but oscillate. Calculating frequency and adjusting on/off ratio will require a little more thought and calculation, but shouldn't be a big deal.
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