In the first of a series of articles we look at one of the component kits that are popular on various sites such as Amazon.
The premise is simple, you buy a kit of similar components in which you get a quantity of each and the price seems appealing but is it.
The first one is a value pack of darlington transistors which you can see the image below.
darlington transistor kit
Parts
First of all lets see what you get, you get 5 each of the following darlington transistors. They are all through hole types, no smt here.
You get 5 NPN and 5 PNP types and if you look at the description below the main difference is the rated output current and voltages.
The prices were taken from RS components in the UK and i’m not an affiliate so nothing to gain, just wanting to show the price on one website. You may be able to shop around and find these cheaper.
| Name | Description | Price each (RS) | |
| tip31c | NPN Transistor, 3 A, 100 V, 3-Pin TO-220 | 0.668 | 3.34 |
| tip41c | NPN Transistor, 6 A, 100 V, 3-Pin TO-220 | 0.533 | 2.665 |
| tip120 | 8 A 60 V HFE:1000, 3-Pin TO-220 | 0.757 | 3.785 |
| tip121 | NPN Darlington Transistor, 5 A 80 V HFE:1000, 3-Pin TO-220 | 0.612 | 3.06 |
| tip122 | NPN Darlington Transistor, 8 A 100 V HFE:1000, 3-Pin TO-220 | 0.555 | 2.775 |
| tip32c | PNP Transistor, 3 A, 100 V, 3-Pin TO-220 | 0.664 | 3.32 |
| tip42c | PNP Darlington Transistor, 10 (Peak) A, 6 (Continuous) A 100 V dc HFE:15, 3-Pin TO-220 | 0.658 | 3.29 |
| tip125 | PNP Darlington Transistor, 5 A 60 V HFE:1000, 3-Pin TO-220 | 0.64 | 3.2 |
| tip126 | PNP Darlington Transistor, -5 A 80 V HFE:1000, 3-Pin TO-220 | 0.705 | 3.525 |
| tip127 | PNP Darlington Transistor, 5 A 100 V HFE:1000, 3-Pin TO-220AB | 0.81 | 4.05 |
| 38.01 |
So the price each is in pounds, it should be noted to get that price on some of these components there is a minimum quantity of 5 at times, sometimes even 25 but all were in stock.
Kit Prices
Now we head onto a few sites and look at some sample prices
| Amazon UK | £15.99 |
| Amazon.com | $15.99 (US Dollars) |
I couldn’t find the same kit on Aliexpress or Ebay – there are plenty of other options, again its buy what you need
For example I saw this listing for 10 TIP32C on Aliexpress for £1.13
10PCS Transistor TIP32 TIP32C PNP / Silicon Controlled Crystal / Darlington Triode TO-220
Again its do you want to wait for delivery, pay shipping costs if they exist or import duty on these components. For me if you plan in advance and it can be up to 28 days buying from Aliexpress can be the way.
The shipping cost was £2.57 for the record on the item above.
Just be careful of ICs, especially older processors – we’ll get to that in a future article.
Summary
So as you can see this does look to be excellent value for money …… if you are going to actually use a decent amount of these transistors. Now bearing in mind that all of the 15 NPN ones would be worth about £19 – there or there about then if you have a generic need then you can use all of these.
What do I mean, well lets say your project did not require higher current or voltage than the lowest rated transistor, in this case the tip31c for NPN then you can easily use all of them in projects as long as you do not exceed it.
Again if you are not going to use about 20 of the transistors in total, you are probably not saving money. Not a lot of money to be fair.
For me that wasn’t an issue and I just wanted the convenience of a nice little box with several types, instead of my usual box filled with random values that I have to sift through.