Here's the link to the drawing I will be basing my questions off of:
#1. Why put a resistor between arduino V+ and transistor base? (Veb) for TIP120 = 5.0VDC = Arduino V+ #1.a. Why specifically 1K OR 2.2K? Why not say, 1.2K? #2 Are these TIP120 transistors ESD sensitive? Do I need to wear a wristband while soldering them to my board? #3. Are these transistors heat-sensitive? Do I need to use a heat sink while soldering? #3.a. Will I need to use a heat sink attached to the transistor during operation? - will be switching 12VDC - #4. has anybody ever used a NTE2343 in place of a TIP120, and if so, does it do the job? #5. Why place the transistor between load and GND? My initial thought would be to place it between V+ and load; would that work? If no, why?
#1: To avoid to exceed the max base-emitter current, and to not dissipate more power than necessary. #1b: 1k and 2.2k are in the E3 series of values everybody has at hand. Other values are rarely needed in the hobby area. And it does not matter very much.... #2 Poppycock! #3 Do limit the solder time to 10 seconds If the transistors are switch at a low frequency rather than used as analogue amplifiers or switched at high frequency you might not need an additional heat sink. You can safely dissipate 1W. #4 You are aware that the TIP120 is a Darlington, aren't you? #5 It is a NPN Transistor, and you want to switch against ground. If not, use a PNP and switch against 12V. However this is generally not a good idea....
Posted by: deSilva Posted on: Today at 13:07:41 #1: To avoid to exceed the max base-emitter current, and to not dissipate more power than necessary. #1b: 1k and 2.2k are in the E3 series of values everybody has at hand. Other values are rarely needed in the hobby area. And it does not matter very much.... #2 Poppycock! #3 Do limit the solder time to 10 seconds If the transistors are switch at a low frequency rather than used as analogue amplifiers or switched at high frequency you might not need an additional heat sink. You can safely dissipate 1W. #4 You are aware that the TIP120 is a Darlington, aren't you? #5 It is a NPN Transistor, and you want to switch against ground. If not, use a PNP and switch against 12V. However this is generally not a good idea....
Thanks! Very informative!
Regarding #4, Yes I am aware that it is Darlington, however I am not aware of what that means. I am but a noob. I will read about that further, sounds important.
If the transistors are switch at a low frequency rather than used as analogue amplifiers or switched at high frequency you might not need an additional heat sink. You can safely dissipate 1W.