Experiments 1.1: Introductory Power Supply Circuit
okay first thing we want to do before we get started just to talk about the breadboard for a second now here's a typical breadboard you can see it's made up of different columns and rows and the columns here are joined together so for example at number one we have five pins that are connected together and then we have a break in the center well we took the Gate Bridge chips across the ground and then we've another set of five pins that are connected together to each other as well so a ter connected together and f2j are connected to go along with this we have two rails two rolls and the ground rail and the +5 volts rails what we're going to use them for you will know if you start on on some horses there's a gap here and it just breaks the rail lines you'd have two different rounds so in our case we want to build our
circuitso that will connect we're going to use both sides of this rail so the first thing we're going to do is just connect a bridge those two gaps with there with a couple of interconnecting wires so press that little wire there okay so now we've bridged the two connections and now we want to set up our circle so we set up our
circuitin the in the corner here so zoom in a little bit to do this now we're going to use a 9-volt battery it's just a normal 9 volt battery DC
supplyand we're going to use a connection cap it's just a cap that goes on tonight volt battery and term 8 some two leads and we're also...
going to use a voltage regulator to set up it in this case we're using an LM 0 5 and the LM 0 5 will accept a
supplyand output around 5 volts the this chip is is organized so that it gives us our our pins are as follows the this pin here at the leftmost pin is our voltage in the middle pin is our ground pin and the rightmost pin here is our our voltage out our 5 volts
supplyAB so we're going to connect that up into our
circuitand we're just gonna plug it in somewhere like this if we were to plug it in this way for example we have problems on our breadboard because we'd be bridging all three pins will be connected and tied together so we've connected in this way and it means that each one of now pins that we're talking about it pins 1 2 and trade and so pin 1 again is voltage out into his ground and pin tree is voltage in so we just take our cap and connected so the pin and tree I'm going to connect into pin 3 now with our
supplypositive and pinned to with our with our ground we're gonna connect our pin 2 to our ground rep and I just want to go over a little bit because I know that pin one is gonna have to be connected to plus 5 volts wrap okay so now having connected to super ash that's our that's our
circuitsetup when I connect into
circuitis hopefully fully working but it's difficult enough trying to make sure that the connections don't that the naked cable isn't touch off each other so we can't...
really see anything we could measure what our voltage
supplyour voltage meter router and measure our voltages so take your multimeter and set it to DC voltage and if we set it to 20 volts here we should be fine to measure so we should be able to measure now our input voltage so this should be around nine volts so we make sure that we get eight point three six volts which is what you would expect from the battery and we should be able to see downer our
supplyand what do we get now this we've got a regulated
supplywell you should see that it's about four point nine six nine seven volts so it means our voltage regulator is working perfectly now it's hard enough to seat us because we of the way our
circuitis set up so we're going to do is we've got a connection a little LED to indicate when our eyes on our
circuitis supplied so we're just choosing a green LED and the specification for this LED is that this a it expects to 3 volts maximum and a roughly current about 232 20 Millions and so when our LED we see that we've two two legs one leg is longer than the other the longer leg is the anode and that's the positive leg and the shorter leg is the cathode and that's the negative leg you'll also notice if you look very carefully at the plastic housing of the LED that there's a little flat area here at the top and that indicates that that's the negative or the cathode so we want to connect this up so I've disconnected the...
battery from this