Now, heres my first Instructable and Ill show you, how to make a small Voltage Inverter (I mean, getting a NEGATIVE Voltage out of a POSITIVE) on you Bredboard.
Some Amplifying circuits need negative voltage to work good. This circuit schould deliver enough current to power a small OpAmp or so.
Step 1: Part List
Now, youll' need some Parts you can easily from you local electronics store.
-1x Bredboard (To mount everything on, you could even use a small Stripboard to solder everthing on)
-1x NE555 (Tiny Timer Chip, the Heart of the Circuit)
-Capacitors: -1x 25 Volt, 47 - 220µF (For Testing, Get more than One ;))
-1x 16 Volt (or Higher), 0.1 - 1µF (Same Here)
-1x 25 Volt (or Higher) 470 - 2200µF
Resistors: -3x 1.5kOhm ( 1k will work,too)
-1x 100kOhm (With this one you could Mess around, so you could use anything between 1k - 820k, Its up to you!)
-2x 1N4001 Diode (You can use nearly every kind of Diode, but prevent using Zener Diodes. They wont work.)
- 9V Battery or other Powersupply (If youre' using a Wallwart, make sure you put some Ripple-filter caps on the powerlines)
Finally, Some LEDs with the color of your choice.2 - 3 or so.
Step 2: Adding the 555Timer Chip
Just Follow the steps to get your Chip working.
Photo 1: The Schematics of the Timercircuit.
Photo 2: Put your 555 on the Board just like this.
Photo 3: Connect the supply pins to V+ and GND. Mouseover the Photo to see which pin is the V+,GND and RESET.
Photo 4: Add a small bridge from Pin 6 to Pin 2.
Photo 5: Add the 1,5k and the 100k Ohm resistors.
Photo 6: Add a Capacitor with something around 0.47µF.
Photo 7: Beware of the Negative and the Positive connections of the cap!
Photo 8: Same as the cap, the LED has a positive and a negative connection,too.
The shorter leg is the (-) negative connection.
Photo 9: Add a 1.5k Ohm resistior and Plug your LED in.
Now, Connect Power. Your LED should blink. If it does, go to Step 3.
If it doesnt, check all connections, and make sure everything is right.
Step 3: Add Diodes and Capacitors
We want this Circuit to Invert our voltage, so well have to add a few more parts.
Photo 1: The whole circuit.
Photo 2: Every electrolytic capacitor has a + and a - connection.
Photo 3: Connect the positive side of your cap with the Output Pin (Pin 3) of your 555.
Photo 4: Same as the Cap, your diodes have got an Anode (+) and a Cathode (-).
Photo 5: Connect your diode like this.From the negative pin of the cap to the side of the diode without the stripe. The side with the stripe goes to GND.
Photo 6: Put your second diode in like this.The striped side goes to the negative connection of the capacitor.Just use a free place for the second pin of the diode.
Photo 7: Big Cap!
Photo 8: Place this with the positive lead to the GND line of your bredboard and the negative lead to the non-striped side of you second diode. Do not connect wrong.This could damage your 555 or you cap!
Photo 9: The finished circuit.
Step 4: Testing
I hope you know, you couldnt drive more than some milliamps of this circuit.
And there are some switching losses, so you wont get -9V if you put +9V onto it.
Thats because of the Diode-Drop Voltage, and because this circuit isnt' very efficient.
These Photos show the performance of the circuit.
I got just abaout 7,4 Volts without any load, and around 6.5 Volts with a LED as load.
I hope you like it!
JG-223 made it!