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Replacement for Transistor SL100

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PHarnoldPH

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Can anyone suggest for replacement of Transistor SL100 for this kind of cuircuit? Please help me. I'm from Philippines.

I need your thoughts and favorable reply guys. Thank you.
 

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A BC337 is similar (But not identical) It has a slightly higher collector emitter current rating and hfe but it has a slightly lower power dissipation. I assume this circuit is a PWM motor speed control which is controlled from the parallel printer port of a computer. As it is a PWM control the transistor should not dissipate very much power as it should be either fully on or fully off. The circuit will only drive a small motor. Also there should be a diode in parallel with the motor to suppress voltage spikes due to the inductance of the motor winding. (Diode + to 5 volts - to collector of transistor.) I would also suggest reducing the value of the 1K base resistor to about 150 ohms to ensure the transistor is fully turned on.

Les.
 
A BC337 is similar (But not identical) It has a slightly higher collector emitter current rating and hfe but it has a slightly lower power dissipation. I assume this circuit is a PWM motor speed control which is controlled from the parallel printer port of a computer. As it is a PWM control the transistor should not dissipate very much power as it should be either fully on or fully off. The circuit will only drive a small motor. Also there should be a diode in parallel with the motor to suppress voltage spikes due to the inductance of the motor winding. (Diode + to 5 volts - to collector of transistor.) I would also suggest reducing the value of the 1K base resistor to about 150 ohms to ensure the transistor is fully turned on.

Les.
Les,

Thanks.
So, BC337 will do it and then I change 1k base resistor to 150 ohms, and also what kind of diode will I add. Sorry I'm just a student. ☺
 
I would think any of the 1N4000 series diodes would be OK From memory I think the 1N4oo1 is 50 volt PIV rating which is plenty for your application with a 5 volt supply. The last digit of the number is an indication of it's PIV voltage rating. I think a 1N4007 is 1000 volts PIV All of these diodes are rated at 1 amp average forward current. You need to make sure the motor that you use does not draw more than 0.5 amps with such a small transistor driving it.

Les.
 
You could use a FET too. Some idea of the motor characteristics will help.

I do agree with the missing diode. The circuit could possibly use a large value base resistor to ground.

Real parallel ports are hard to come by and sometimess a simulated one (USB to parallel) won;t work at all. This is especially true with CNC interfaces.

There's the question as to where you shop fro parts? Thanks for giving a geographical location.
 
PHarnoldPH,
you could also use BD139 and i suppose they are adequately available.
they have some china substitutes with 4 digit number
 
I'm from Philippines.
I use to live in the Philippines. I was in the Navy stationed at Subic Bay, near Olongapo. That was back around 1980.
 
Are we making too much of discussion , just on a relay drive transistor? The purpose is too simple.
 
Are we making too much of discussion , just on a relay drive transistor? The purpose is too simple.
Not really, the link for example may help others.
 
what i meant, little ghostman, is that the discussion rather confuses users. Even a general purpose transistor like BC547 could drive a motor, unless the motor is a heavy duty needing 1 amp operating current.
 
Fair enough, to be honest i didnt look at the circuit:sorry:, I had a link that I kind of felt would be useful for other posts in the future. But yes for a motor just about most will do, except the OP might not have any or know this?
 
Can anyone suggest for replacement of Transistor SL100 for this kind of cuircuit? Please help me. I'm from Philippines.

I need your thoughts and favorable reply guys. Thank you.

Hi PH,

There is nothing special about transistor, T1, on your circuit board, or its function. Here is the data sheet for the SL100: https://www.engineersgarage.com/sites/default/files/SL100_0.pdf

(1) Transistor T1 equivalents
As LG shows in his post #9 link, there are many transistors that would do your job.

(2) Transistor important characteristics
The only important characteristics for T1 your circuit board are:
(1.1) Transistor type: NPN silicon bipolar junction transistor (BJT)
(1.2) Case: T0-39 or T0-5
(1.3) Power (Ptot): at least 800 mili Watts (0.8 Watts)
(1.4) Collector current: at leat 500 mili Amps (0.5 Amps)
(1.5) Collector Emitter Voltage (VCE): at least 10V (most transistors would be at least 30V)

Just ask your local, or internet electronics store for a transistor to meet the above specification and they will fix you up.

As the transistor needs some heat sinking, according to your diagram, an all-plastic case transistor would not be suitable.

(2) Some specific replacement transistors
(2.1) To use the existing heat sink you need a transistor with a TO-39 or TO-5 metal case: BFY50x, BFY52x, 2N3053x
https://www.farnell.com/datasheets/13478.pdf

(2.2) If you have the space, as mvs has suggested, fit a TO-126 plastic/metal case: BD139x,
https://www.fairchildsemi.com/datasheets/BD/BD135.pdf

(2.3) Or bigger TO-220 plastic/metal case: TIP31x:
https://www.fairchildsemi.com/datasheets/TI/TIP31C.pdf

(x after part number indicates that any suffix part will do. For example TIP31. TIP31A, TIP31B, TIP31C)

(3) Recommended Transistors
The BD139 and TIP31 are the best choice if they will fit. I would think that the original transistor is a bit weak for driving a motor- that may be why it has failed.

(4) T1 Base drive
The value of R3 should be reduced from 1K to around 220 Ohms as Les has suggested (150 Ohms) to put more current into the base of transistor T1, and ensure it is turned on fully. Paradoxically, this will help protect transistor T1.

(5) Protection diode
Also as Les recommends, a diode should be connected across transistor T1 (cathode to collector and anode to emitter) to protect the transistor from negative voltages generated by the inductance of the motor. A 1N4oox diode would be suitable or any other 1A or more 10V or more rectifier diode. As the supply line is only 5V, a positive catching diode should not be needed.

(6) Decoupling
The circuit also needs some decoupling across the 5V supply line: 470 micro Farads minimum aluminum electrolytic capacitor in parallel with a 100 nano Farad minimum ceramic capacitor. Both capacitors should have a voltage rating of at least 7V. The electrolytic capacitor must have its positive terminal connected to the 5V supply line and not the other way around. It does not matter which way around the ceramic capacitor is connected, because it is not polarised.

spec
 
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