10 Channel Light Bulb Sequencer - Page 2 - Electronic Circuits Projects Diagrams Free

**kinjalgp** · 18th January 2008, 11:06 PM

Quote:

Originally Posted by jumides

hi kinjalgp,
I see schematic, but what happen to 4017, if BT139 goes wrong(short circuit) ?.

Well, it totally depends upon the type of failure of BT139. If there is leakage from gate .... it will blow up 4017 in worst case. However I haven't seen such kind of failure.
To avoid triac failure, never connect load beyond its rated capacity.

**Nigel Goodwin** · 19th January 2008, 09:50 AM

Quote:

Originally Posted by kinjalgp

To avoid triac failure, never connect load beyond its rated capacity.

And never use them to feed bulbs, because when the bulb fails it almost always takes out the triac at the same time.

Bit difficult for a light sequencer though?.

shokjok · 22nd May 2008, 03:37 AM

The 4017 would quickly self-destruct. I built a similar circuit using MCT2 optos and T106 triacs to control Christmas lights ( up to 200 per triac, fused). A smaller version using 2N3904s alone turned on LEDs as a mini name-in-lights project, with 6 recipients.

**kinjalgp** · 22nd May 2008, 03:55 AM

Quote:

Originally Posted by Nigel Goodwin

And never use them to feed bulbs, because when the bulb fails it almost always takes out the triac at the same time.

Bit difficult for a light sequencer though?.

Quote:

Originally Posted by shokjok

The 4017 would quickly self-destruct. I built a similar circuit using MCT2 optos and T106 triacs to control Christmas lights ( up to 200 per triac, fused). A smaller version using 2N3904s alone turned on LEDs as a mini name-in-lights project, with 6 recipients.

I doubt if that would happen ! When bulb fails, it becomes open circuit ! How will that affect the TRIAC ??
I have been using this circuit for years now with quite a lot bulb failures, never had to replace a TRIAC or 4017 yet!
Can you explain ?

Gayan Soyza · 22nd May 2008, 04:20 AM

I’m away of this BT series TRIACs. For running lights its ok but when it comes to sensitive light dimming (Phase Controlling) this series acts poor.

I’m using TIC216 or BTA16-600B because they don't seem to suffer from any dv/dt problems.

**Nigel Goodwin** · 22nd May 2008, 09:30 AM

Quote:

Originally Posted by kinjalgp

I doubt if that would happen ! When bulb fails, it becomes open circuit ! How will that affect the TRIAC ??

As bulbs fail they commonly go S/C before they go O/C, this kills the TRIAC's - it's a VERY, VERY common fault on light units. I've made a lot of money over the years repairing light units damaged in this way

22nd May 2008, 04:20 AM	(permalink)
Gayan Soyza Experienced Member Blog Entries: 1	I’m away of this BT series TRIACs. For running lights its ok but when it comes to sensitive light dimming (Phase Controlling) this series acts poor. I’m using TIC216 or BTA16-600B because they don't seem to suffer from any dv/dt problems. __________________ Gayan Forum Supporter

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22nd May 2008, 03:37 AM	(permalink)
shokjok Experienced Member	The 4017 would quickly self-destruct. I built a similar circuit using MCT2 optos and T106 triacs to control Christmas lights ( up to 200 per triac, fused). A smaller version using 2N3904s alone turned on LEDs as a mini name-in-lights project, with 6 recipients.