This is a placeholder topic for “Transistor Pack (170 pcs)” comments.
This package includes 17 species transistors in common use.It’s convenient for you to make some small designs.You could find a suitable one for your type!
Read moreI have this pack of transistors and… I dunno there are so many and I’m sure they all have different properties. Hard to know what transistor to chose when I realize I need one.
For instance in this case I have a 12v halogen light and I want to turn it off and on with a momentary push button. The push button won’t handle 12v so I need some 5v logic and a transistor or mosfet. I measured my halogen to require 110ma so I have some idea of my requirements.
What I’d like to do now is to look up a big csv file or spreadsheet with all the common transistors and look for one that matches my need but I really can’t find one.
Does a big spreadsheet or famous website exist?
How do other people figure this out?
Not much of a push button.
You can do this easy enough with 2 buttons for on and off but one button is a bit more complicated. Will have a think. Maybe you need a dual RS flip flop.
I think most of the transistor types n these packs might be in the Jaycar catalog. This gives a quick run down on pertinent specs without going into the gory detail. The first thing to do is to sort the different numbers.
Cheers Bob
Cheers Bob
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Clever. I have a paper copy I can refer too. Nice! 
I actually have a plan and a schematic. I might actually start a stand alone thread for it if your curious or have some feedback.
You can find that below. 
Hi Pix
I was just about to tell you you would need the paper catalog. I just looked and I can’t find a list like that on the Jaycar site.
That circuit should work. First time too. Hooray
Cheers Bob
I’m decorating myself with an Improvement Award! 
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Hi @Pixmusix
From what I’m aware there isn’t a database like that (although it would be a great tool to have), my preference for finding the right one would be to go to somewhere like RS-online, Mouser or Digikey and use their filters to select the parameters that I need.
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Hi Dan
Back in the dark ages magazine publishers and the like used to publish comparison charts like replacement charts particularly due to the different numbering systems.
Nowadays it seems that there seem to be 2 generic types that will do most things (according to Jaycar anyway), PN100 (NPN) and PN200 (PNP). sort of one size fits all. Could be right too as transistors are pretty forgiving beasts as long as you don’t overdo it.
Element 14 are pretty good too for ths sort of thing with the added advantage of data sheets for most of the products they sell.
Cheers Bob
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For future readers I settled on the S8050 from this set because it has a high continuous collector current.
The PN100 is another good choice. I’m pretty sure I have some and should consider using those.
Seems like this pack is full of lot’s of weird and fun transistors. Recommended uses like frequency amplification and super high voltage. I may never need them, but it’s nice to know that they’re in the pocket.
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Hi Pix
That transistor should do the job. The only doubt would the amount of current capability of the IC. The best I could find from he data sheet is sourcing 0.4mA. This means you may have to increase the base resistor to about 10k to stay within this figure. Then if that particular transistor has hfe less than about 250 it probably won’t turn on.
Nothing is ever easy.
Cheers Bob
It’s a really weird transistor. Super high hFE and 700ma continuous current.
- Maximum DC Current Gain (hFE) is 400
- Continuous Collector current (IC) is 700mA
- Base- Emitter Voltage (VBE) is 5V
Based on this webpage.
Still. I am thinking of using the PM100 since I have more of them and I’d like to use them up. They’re perfect for this application. I can drop them right into the circuit I’ve already designed.
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I like this too. I needed it for some of the more rare transistors in this list.
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Hi Pix
Unfortunately transistors tend to have a very wide range when it comes to hfe particularly.
Your link states 400, a couple of data sheets I see quote for 100mA collector current a hfe of 85 - 300. Make of that what you will. Most real commercial designers design for the lower side as a commercial manufacture cannot be expected to use selected components. Even during repair you would expect a replacement to work, not expected to have to select from a batch.
So your transistor might or might not work. Unfortunately ICs sometimes have a range of numbers for different bits of data. So the circle continues.
It seems both you and Gerard163258 have been blessed with similar problems, namely lack of enough drive current for the switching device.
If your system does not work or is a bit iffy there are a couple of things you can do:
interface a rail to rail OpAmp (such as LMC6482) between flip flop and transistor connected as a voltage follower to supply the current. This is a dual unit so the second device can be used with another switch.
Find another R/S flip flop that will do the same job but more source current capability.
Cheers Bob
Gotcha.That’s helpful too keep in mind. Thanks Bob.
I have a lot of these lying around so I can always test and measure.
If after testing I find it all too inconsistent I can try the P100 or even a relay or mosfet.
Hi Pix
You will still have the dreaded current (or lack of) problem to drive any sort of switch.
Cheers Bob
Hi Pix
Just did a bit of research.
Try the 74HC73. No one lists a max and min output current but the absolute maximum ratings are given as +/- 25mA. (sink and source) which gives you a chance of a few mA to drive your transistor. You might even go lower than 3k3Ω to make sure of switch on.
If you have source trouble Jaycar stock these.
Cheers Bob
Isn’t the point of a mosfet that it’s voltage controlled? Do they care at all about amps?
Hi Pix
Yes they do. As I have pointed out on many many occasions a Mosfet has a gate capacitor which has to be charged That is CURRENT. It is a short circuit at switch on (as is any capacitor) so the current can be relatively substantial.
Cheers Bob
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Right. I guess its intuitive to me that 5v 0amps is not going to switch a mosfet on.
I suppose if this is a problem I actually could use a transistor between the flip flop and the gate to ensure current.
Hi Pix
You don’t seem to be getting it.
A Mosfet requires cap charging current at switch on. After the initial “inrush” it then requires the voltage to remain on, the current is minuscule, µA or even pA.
A transistor requires current to turn on and remain on.
I don’t think your flip flop can provide that current
You would not get that. You would probably get the flip flop output sagging to a low value and ultimate failure or at best a long switch on time for the Mosfet with some possible accumulative flip flop damage with possible ultimate failure.
Cheers Bob
