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A simple Voltage Regulator |
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(for battery operated devices) |
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| Using a common 7805 fixed voltage regulator | This regulator is desirable if you have a bunch of | |||||||||||||
| found at Radio shack , it is possible to design a | battery operated devices which accept an external | |||||||||||||
| custom voltage output regulator for $2.00 | power source. You can eliminate all your batteries | |||||||||||||
| which is current limited to slightly more than 1 amp | as you can design any voltage you like between 5-10vdc as an output. | |||||||||||||
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The base Formula for modifying the cheap regulator is |
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Vout = V(designed)\(1 + R2/R1) + (Iq * R2) |
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So, for a common 7805 fixed 5 volt regulator |
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Vout =5(1 + R2/R1) + (Iq * R2) |
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Where Iq = .0042 (4.2 ma) and you experiment with the values of R1 and R2 |
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| An Example: | ||||||||||||||
| For a regulated output of | Here is the package and pin outs for the IC | |||||||||||||
| 9.35 | volts |
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| Vout = 5(1+1000/33000)+(.0042*1000) | ||||||||||||||
| Use the following components | ||||||||||||||
| C1 | 0.33 | uf | ||||||||||||
| C2 | 0.1 | uf | ||||||||||||
| R1 | 33000 | ohm | ||||||||||||
| R2/VR1 | 1000 | ohm | ||||||||||||
| Note: R2 can be a variable resistor and | ||||||||||||||
| the circuit becomes a variable power supply | ||||||||||||||
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