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Step 9: Transistors

A transistor takes in a small electrical current at its base pin and amplifies it such that a much larger current can pass between its collector and emitter pins. The amount of current that passes between these two pins is proportional to the voltage being applied at the base pin.

There are two basic types of transistors, which are NPN and PNP. These transistors have opposite polarity between collector and emitter. For a very comprehensive intro to transistors check out this page.

NPN transistors allow electricity to pass from the collector pin to the emitter pin. They are represented in a schematic with a line for a base, a diagonal line connecting to the base, and a diagonal arrow pointing away from the base.

PNP transistors allow electricity to pass from the emitter pin to the collector pin. They are represented in a schematic with a line for a base, a diagonal line connecting to the base, and a diagonal arrow pointing towards the base.

Transistors have their part number printed on them and you can look up their datasheets online to learn about their pin layouts and their specific properties. Be sure to take note of the transistor's voltage and current rating as well.
<p>what do you mean by 'Ground'?</p>
<p>For any soon-to-be electronic enthusiasts, &quot;Arduino&quot; is something for you to look into.</p>
<p>I totally agree. <a href="http://amzn.to/1sa0y8O" rel="nofollow">There is a great 'starter kit' on Amazon</a> that includes a full color manual. </p><p>I bought this for my Son and he had a great time going through all the different tutorials!</p>
<p>Nice kit, but I would recommend the new <a href="http://www.amazon.com/dp/B01EKO6FZU" rel="nofollow">Make: Electronics Component Kit 2nd Edition</a> for a beginner in the field as it will teach them all of the circuits and electronic theories they need to know before getting into Arduinos. This kit has all the components for the beginning of the new Make: Electronics 2nd ed book which is the best book for newcomers looking to learn electronics and build circuits.</p>
<p>Thank you so much! I will buy that one first. If something is explained from scratch, I can grasp it, but with missing steps I get confused and discouraged. That's why I am liking this website too. If I had gotten arduinos first, I would have probably gotten confused. I am planning to get arduinos, but after I get the kit you recommended. </p>
<p>Yeah, this is a good kit. Not having the additional complexity of learning Arduino code is a plus for sure.</p><p>But, you can't go wrong with either kit! :)</p>
<p>supr</p>
I'm starting out in electronics and on a schematic when a wire seems to split off two ways on a right angle that just means it is connected to both of those components correct?
<p>Hi !</p><p>I am vinay and I want to enlighten a 12 LED by the battery of my bajaj caliber 115 motorcycle, I want to know how can I use CD 7812 voltage regulator to get a constant 12 V DC while the bike is running ( when it will produce around 14.5 V).</p>
when you say ground do you mean negative<br>
Expertman, In early Electronics, ask about anything that you feel uncertain about. Its a &quot;grey&quot; area, an important question. In response, &quot;Ground&quot; and &quot;Negative&quot; are used with the same intent.They refer to the &quot;polarity&quot; of the power supply(Battery in this case) and where the 'pin' of a component's intended destination is(These components are usually labeled with this, if necessary) if unsure, find it online-(Not in a 'Blog', use 'DIGIKEY') Great prices, too!<br>. Good luck, hope this helped!
<p>i guess in both images,, wires are connected in parallel...</p>
i've been looking for this all over the endless fields of the internet. so, just tanks a lot
<p>Value the admission you delivered.. Certainly helpful <br>perception, thanks for giving.. Loving the contribution.. best wishes I <br>appreciate you expressing your viewpoint..</p><p>http://www.huludb.com/</p>
<p>apt site for beginners</p>
<p>This was very educational and informative for me thanks</p>
<p><strong>nice site for beginners as well as professionals</strong>.</p>
<p>Michael U.</p><p>Thanks alot for this tutorial, it is so rich</p>
<p>Hi,<br><br>Thank you so much for this tutorial.<br><br>FYI , on step12 (ie LED) you mentioned that the flat notch indicator is on anode end , but its on cathode end of the LED. Please check it.<br><br>Thanks.</p>
<p>Thanks for this tutorial!<br><br>For all electronic fans, I made a site about basic stuctures used in analog electronic:<br><br><a href="http://shematronic.ddns.net" rel="nofollow">http://shematronic.ddns.net</a></p>
<p>I appreciate this tutorial. However, where can I go, not to find circuits, but more specifics on how circuits work. I can understand how the first circuit works , sort of understand how and why the second circuit works, and am more lost on the third one. I'd like more of an explanation on why resistors and capacitors are used in specific situations. Any suggestions?</p>
<p>For the &quot;Your second circuit&quot; section, is it 2N3906 PNP and 2N3904 NPN or should the PNP and NPN be switched? The parts list does not match the image of the circuit. </p><p>I'm a beginner, and I want to make sure I use the correct parts.</p><p>Thanks</p>
thanks... good for start<br>
<p>Thanks, this was exactly what I needed. A nice improvement would have been to explain why each element was on the circuit, instead this feels like you just follow instructions without knowing what you are doing. But once again, it's a perfect introduction to ultra beginners like me.</p>

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Bio: My name is Randy and I founded the Instructables Design Studio. I'm also the author of the books 'Simple Bots,' and '62 Projects to ... More »
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