BeginnerPower
Build a 5 V Linear Breadboard Supply
Regulate a suitable low-voltage DC input to 5 V with an LM7805, then measure its load and heat limits.
Parts from the database
- LM7805 × 1Fixed 5 V regulator
Other supplies
- 9 V regulated DC adapterCommon build supply
- 330 nF input capacitorCommon build supply
- 100 nF and 10 µF output capacitorsCommon build supply
- breadboard rated for the currentCommon build supply
- multimeterCommon build supply
- optional heatsinkCommon build supply
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Connections
- Check the package datasheet; the common TO-220 order viewed from the marked face is input, ground, output.
- Adapter positive to IN, negative to GND. Put 330 nF from IN to GND and 100 nF close from OUT to GND; observe electrolytic polarity for 10 µF.
- Connect output and ground to breadboard rails and measure before attaching another circuit.
Build steps
- Measure adapter voltage and polarity first.
- Power regulator unloaded and verify near 5 V.
- Add a small known load and monitor voltage and temperature.
- Estimate heat as (Vin−5 V)×load current; reduce current/input or heatsink as needed.
Software and firmware setup
This is a hardware-only circuit; no firmware is required.
Test your build
Output stays near 5 V under a modest load without exceeding thermal limits.
Troubleshooting
- Wrong voltage: disconnect and verify package pinout.
- Overheating: reduce voltage drop or load current; assess heatsinking.
- Output dips: check adapter capacity and local capacitors.
Safety and limitations
Low-voltage DC only. Use an enclosed certified adapter; never wire the regulator to household mains.
Manufacturer and platform documentation
Community Notes for This Project
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