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What are the alternatives i can use for SL100 Transistor and BT44 Triac?

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Clarkdale44

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Hello

I am thinking of building the below circuit but i am short on components. I have all the others except SL100 transistor and BT44 triac which i can't seem to find in any local store. If anyone can tell me what alternative components i can use for these two then please let me know i would really appreciate it.

The circuit diagram. I found it here
 

spec

Well-Known Member
Most Helpful Member
Hy Clarkdale44,

Have no fear there are a number of alternatives for your parts- there is nothing particularly special about them.

I don't have time at the moment to suggest replacements but will probably be able to do so within 24Hrs.

I'm sure other ETO members will respond too.

Just a word of caution: it is not wise to have 240V wiring in your garden. Much safer to use 12v say.

spec

PS: can you specify what the lamp is: type, wattage?
 
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schmitt trigger

Well-Known Member
The only real concern is to find a 4 quadrant trigger Triac.

The reason is that the Triac is triggered with positive current. If you were to mirror all of the trigger circuit to apply negative trigger current, more common 3 quadrant Triacs could be used.
 

spec

Well-Known Member
Most Helpful Member
The only real concern is to find a 4 quadrant trigger Triac.

The reason is that the Triac is triggered with positive current. If you were to mirror all of the trigger circuit to apply negative trigger current, more common 3 quadrant Triacs could be used.
Hy Clarkdale44,

In view of schmitt trigger's point above are you happy to use a compliment of the circuit.

I could redraw the complimented circuit if required

Not only will this allow a wider choice of TRIAC but it will also allow the use of 'high commutation' TRIACS which switch more reliably with a range of loads without the need for added commutation circuitry.

spec
 

Clarkdale44

Member
Hy Clarkdale44,

In view of schmitt trigger's point above are you happy to use a compliment of the circuit.

I could redraw the complimented circuit if required

Not only will this allow a wider choice of TRIAC but it will also allow the use of 'high commutation' TRIACS which switch more reliably with a range of loads

spec
Well , as long as it works according to my needs, i don't have any problem with changes. The indecent 230v 100W is just an example load. What i want to run at the moment is a led bulb rated at 9w, that has it's own circuitry and takes 230v input from the same bulb slot. I may use 100W bulb in future so a maximum draw of 100W output is must, rest depends on how much the connected load draws.
Also it's not for my garden, but for my room for night time. I want the bulb to turn on automatically at night and stays off during day time.. That's all.
 
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spec

Well-Known Member
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Hy again Clarkdale44,

Here are suitable replacements for the components in the original circuit. As you will not be switching inductive loads there should be no commutation issues:
(1) TRIAC: NXP BT136-600E http://www.nxp.com/documents/data_sheet/BT136-600E.pdf
(2) Transistor: pretty much any NPN small signal bipolar junction transistor will do: BC337 would be ideal. http://www.onsemi.com/pub_link/Collateral/BC337-D.PDF

Some other suitable transistors are:
BC546, BC547, BC548, BC549, BC550. Data sheet: https://www.fairchildsemi.com/datasheets/BC/BC547.pdf
BC107, BC108, BC109. https://www.centralsemi.com/get_document.php?cmp=1&mergetype=pd&mergepath=pd&pdf_id=bc107.PDF
BC182, BC183, BC184. http://www.astlab.hu/pdfs/BC182.pdf
2N3707, 2N3708, 2N3709, 2N3710, 2N3711. http://www.mouser.com/ds/2/68/2n3707-3711-15606.pdf
2N3903, 2N3904. http://www.onsemi.com/pub_link/Collateral/2N3903-D.PDF
2N2222, PN2222. http://www.onsemi.com/pub_link/Collateral/2N2222A-D.PDF https://www.fairchildsemi.com/datasheets/PN/PN2222.pdf

spec
 
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spec

Well-Known Member
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while you can follow spec with BT136, you may try 2n5551 in place of SL100.
You do not need a high voltage transistor in that position in the circuit, even though the circuit is mains driven.

The most vulnerable aspect of the transistor is the reverse emitter base voltage limit which is only 6V for the 2N5551.

spec
 

spec

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OK spec, I get you.
No probs mvs,

When I first saw the circuit I too thought the transistor should be high voltage type. But the 12V Zener limits the voltage that the transistor sees.

spec
 

Willen

Well-Known Member
The only real concern is to find a 4 quadrant trigger Triac.

The reason is that the Triac is triggered with positive current. If you were to mirror all of the trigger circuit to apply negative trigger current, more common 3 quadrant Triacs could be used.
Hi,
'Quadrant' (3 or 4) term sounds new to me in Triac, I didn't read before. May I know about it in simple?
 

spec

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Most Helpful Member
Hi,
'Quadrant' (3 or 4) term sounds new to me in Triac, I didn't read before. May I know about it in simple?
Hy Willen,

Triac quadrants are dead simple:

upload_2016-7-9_11-48-26.pngupload_2016-7-9_11-45-16.png


(1) Equivalent Circuit
(1.1) The name triac is derived from 'triode for AC' which is a complete misnomer.
(1.2) The image on the left shows that the equivalent circuit of a thyristor comprises two complementary transistors, and the image on the right shows that the equivalent circuit of a triac is two thyristors connected in reverse parallel. You can actually make a thyristor from an NPN transistor, a PNP transistor, and a couple of resistors. It thus follows that you could make a triac from two NPN transistors, two PNP transistors and a few resistors.
(2) Trigger
(2.2) A triac switches AC current and is turned on by a signal between the gate and anode 1, when there is a voltage, either positive or negative, on anode 2.
(2.3) Triacs cannot be turned off by a signal on the gate (gate turn off [GTO] devices can be turned off by the gate signal).
(2.4) Once conducting, triacs can only be turned off is by reducing the anode current to below the triac holding current.
(2.5) The gate signal is typically 1.2V at a current of 500uA, 1mA_5mA_10mA, 20mA, 30mA, 50mA, 100mA or 150mA, depending on the triac. Normally the higher current triacs require higher gate current to trigger.
(3) Quadrants
(3.1) There are four relationships that can occur with the gate signal:
(3.2) Anode2 positive, gate positive (quadrant #1)
(3.3) Anode2 positive, gate negative (quadrant #2)
(3.4) Anode2 negative gate negative (quadrant #3)
(3.5) Anode2 negative gate positive (quadrant #4)
(for some bizarre reason Anode 1 is also known as Main Terminal 1 (MT1) and Anode 2 is known as MT2)
(3.6) Early triacs generally triggered in all four quadrants, but some of the new 'High Commutation' (HiCom) triacs only trigger in quadrants one, two, and three (some HiCom triacs will trigger in quadrant four, but only at a higher current, typically double).
(4) Commutation
(4.1) With certain loads, especially inductive, normal triacs may not trigger or falsely trigger, so you need to fit snubber circuits, but theses can get quite complex and expensive, especially where high voltages and currents are involved.
(4.2) Because of this, a new breed of triacs were introduced. These are known as HiCom types. http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00002263.pdf
(4.3) HiCom triacs only trigger in three quadrants and they generally need more trigger current (but not more voltage). Typical HiCom triac trigger current would be 50mA or 100mA for a 20 Amp to 50 Amp TRIAC.
(5) Logic Level
(5.1) There is another breed of triacs know as 'Logic Level'. Theses have trigger currents of 500uA to 10mA and can be triggered by logic circuits, including MCUs.
(5.2) Logic Level TRIACs generally trigger in four quadrants and are not HiCom types. They also tend to be limited to lower currents, around 10 Amps maximum.
(5.3) But recently, another breed of Logic Level triacs have been introduced which are HiCom and only trigger in three quadrants. http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.DM00104272.pdf
(6) Maximum Voltage and Current Change Rate
(6.1) Two things that often gets missed when using triacs (and thyristors) are the maximum rate of voltage change (dV/dt) and maximum rate of current change (dI/dt). If you exceed the former the triac can turn on without a gate signal, and if you exceed the latter the triac can be damaged.

spec

LINKS
(1) http://www.nxp.com/documents/application_note/APPCHP6.pdf
 
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