Socket DIL inquiration - Page 2 - Electronic Circuits Projects Diagrams Free

Boncuk · 22nd August 2008, 02:22 AM

Hi Muhammad89,

just to emphasize audioguru's statement about thyristors: They behave like a self-latching relay applying DC. Removing or inverting the gate voltage they still conduct.

I don't suggest usage of thyristors for that reason. You might power the traffic lights using appropriate transistors.

You will also have to remove the supply voltage and/or short the thyristor.

For schematic and PCB software you might also download Eagle at http://www.cadsoft.de. The light version is free with limitiations of the max. board size of 3.15X3.15" and one sheet in the schematic editor.

Boncuk

Muhammad89 · 22nd August 2008, 04:57 PM

HI bonk Uk,

What if a timer is used in the circuit, such as 555 timer chip, that is just to keep the shorting of the thyristor to go automatically after a proper period of time and make the changing over between the three lights go smoothly?

audioguru · 22nd August 2008, 07:04 PM

If you must use a circuit to short the thyristors then the circuit can drive the LEDs and the thyristors are not needed.

Muhammad89 · 22nd August 2008, 07:31 PM

Quote:

Originally Posted by audioguru

If you must use a circuit to short the thyristors then the circuit can drive the LEDs and the thyristors are not needed.

In this kind of application I want to consider the usage of the Thyristor much than the Timer, how much do you think of the possibility of using the thyristors alone in such circuit ?

Muhammad89

audioguru · 22nd August 2008, 08:57 PM

The circuit is not in this thread.
A triac is used in an AC light dimmer. It turns itself off each half-cycle so it needs to be turned on again over and over if you want lights to remain on.
An SCR is half-wave so it lights light bulbs dimmly with AC. It turns itself off each cycle so it also needs to be turned on again over and over if you want lights to remain on.

An SCR is used in a DC alarm system. It stays turned on after it is triggered for a moment.

Transistoirs or Mosfets turn on DC traffic lights and are driven by a sequencer circuit.

Muhammad89 · 22nd August 2008, 09:01 PM

Quote:

Originally Posted by audioguru

The circuit is not in this thread.
A triac is used in an AC light dimmer. It turns itself off each half-cycle so it needs to be turned on again over and over if you want lights to remain on.
An SCR is half-wave so it lights light bulbs dimmly with AC. It turns itself off each cycle so it also needs to be turned on again over and over if you want lights to remain on.

An SCR is used in a DC alarm system. It stays turned on after it is triggered for a moment.

Transistoirs or Mosfets turn on DC traffic lights and are driven by a sequencer circuit.

What is a sequencer circuit ?

Muhammad89

audioguru · 22nd August 2008, 09:38 PM

A CD4017 is a sequencer circuit. It has one output go high one after the other.
A traffic light is driven by a sequencer circuit because the colours light one after the other in a sequence.

Muhammad89 · 22nd August 2008, 09:50 PM

Quote:

Originally Posted by audioguru

A CD4017 is a sequencer circuit. It has one output go high one after the other.
A traffic light is driven by a sequencer circuit because the colours light one after the other in a sequence.

I think I have a Schematic of that, but it doesnt seem to be using the SCR, it is just using the typical diode.
here it is http://www.kpsec.freeuk.com/projects/trafficlight.htm
what do you comment?

Muhammad89

audioguru · 22nd August 2008, 10:37 PM

The project is used for toys. The diodes form OR gates so the green LED is turned on for twice as long as the amber LED. The amber LED is turned on for only two clock periods.

If it used SCRs then the lights would be on all the time (unless you short the SCR to turn it off).

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22nd August 2008, 02:22 AM	(permalink)
Boncuk	Hi Muhammad89, just to emphasize audioguru's statement about thyristors: They behave like a self-latching relay applying DC. Removing or inverting the gate voltage they still conduct. I don't suggest usage of thyristors for that reason. You might power the traffic lights using appropriate transistors. You will also have to remove the supply voltage and/or short the thyristor. For schematic and PCB software you might also download Eagle at http://www.cadsoft.de. The light version is free with limitiations of the max. board size of 3.15X3.15" and one sheet in the schematic editor. Boncuk __________________ Proper Planning Prevents Piss Poor Performance

22nd August 2008, 04:57 PM	(permalink)
Muhammad89	HI bonk Uk, What if a timer is used in the circuit, such as 555 timer chip, that is just to keep the shorting of the thyristor to go automatically after a proper period of time and make the changing over between the three lights go smoothly?

22nd August 2008, 07:04 PM	(permalink)
audioguru	If you must use a circuit to short the thyristors then the circuit can drive the LEDs and the thyristors are not needed. __________________ Uncle $crooge

22nd August 2008, 08:57 PM	(permalink)
audioguru	The circuit is not in this thread. A triac is used in an AC light dimmer. It turns itself off each half-cycle so it needs to be turned on again over and over if you want lights to remain on. An SCR is half-wave so it lights light bulbs dimmly with AC. It turns itself off each cycle so it also needs to be turned on again over and over if you want lights to remain on. An SCR is used in a DC alarm system. It stays turned on after it is triggered for a moment. Transistoirs or Mosfets turn on DC traffic lights and are driven by a sequencer circuit. __________________ Uncle $crooge

22nd August 2008, 09:38 PM	(permalink)
audioguru	A CD4017 is a sequencer circuit. It has one output go high one after the other. A traffic light is driven by a sequencer circuit because the colours light one after the other in a sequence. __________________ Uncle $crooge

22nd August 2008, 10:37 PM	(permalink)
audioguru	The project is used for toys. The diodes form OR gates so the green LED is turned on for twice as long as the amber LED. The amber LED is turned on for only two clock periods. If it used SCRs then the lights would be on all the time (unless you short the SCR to turn it off). __________________ Uncle $crooge