DIY Professional DSLR Power Supply (8V/1A) with Overvoltage Protection

If you use your DSLR or mirrorless camera for long studio shoots, video recording, or time-lapses,as a Webcam for streaming or sum, relying on standard batteries is frustrating. Commercial AC adapters exist, but cheap ones often lack proper regulation and safety features, risking your expensive camera.

This project guide will show you how to build a good qualityt, ultra-clean 8V, 1A Constant Voltage/Constant Current power supply. It features an LC ripple filter, native current limiting, and a hard-acting SCR crowbar overvoltage protection circuit that instantly blows a fuse if anything fails to make sure your camera always stays protected : )

Here we are gonna be making a LPE10 dummy pack which is nom. 7.4v and 8.2v max but the circuit can be easily changed to fit any type of other battery even for nikon,sony etc, just by changing the resistor values connected to ADJ pin of LDO IC.

For input power you can use a 12v Battery, a usb with 9-12v output, or 3S Li-ion/Li-ion/LiFEPO4 battery, if you wanna use usb with 5v 2A min Output then use a XL6019 or similar module to bump up the voltage to 10v.

Tools and Components Needed

Before heating up your soldering iron, gather all your components. i have optimized this build to use common components that you can easily combine if you don't have the exact values.

Power Conversion & Filtering

1. Input Source: 12V DC power adapter or battery.
2. Fuse: 1A Glass Fuse with PCB-mount fuse clips.
3. L1 (Inductor): 220uH Inductor.
4. C1: 470uF 16V Electrolytic Capacitor.
5. C2: 220uF 25V Electrolytic Capacitor (Substituted for 100uF for superior ripple filtering).
6. C3: 100nf Ceramic Disc Capacitor

Linear Regulation Stage

1. IC1: LM317T Linear Voltage Regulator (TO-220 package) + Clip-on Aluminum Heatsink(optional but reccomended if u use 12v).
2. D1, D2: 1N4007 Rectifier Diodes.
3. R1 (Top Resistor): 220ohm + 22ohm soldered in series (creates a 242ohm bridge).
4. R2/R3 (Ground Chain): 1k ohm + 300ohm soldered end-to-end in series (creates a precise 1.3ohm to ground).
5. C5: 10uF / 50V Electrolytic Capacitor.

Current Limiting & Crowbar Protection

1. Rsc (Current limit): 7 times 10ohm(1/4W) resistors bundled in parallel to create a 1.4ohm power-resistor.
2. ZD1: 8.2V (1W) Zener Diode.
3. SCR1: BT151-800R Silicon Controlled Rectifier (TO-220 package).
4. C4: 10UF 50V Electrolytic Capacitor (Output backup).
5. C6 (Bypass): 100nF Ceramic Disc Capacitor (Placed at the very end of the line just at the pins of DSLR connection).

Enclosure & Connection

1. Double-sided PCB Perfboard.
2. 2-Pin Screw Terminals (for Input/Output connections).
3. An old, dead camera battery shell matching your camera model (e.g., LP-E10), or more easily get a dummy battery shell without the power supply for cheap.
4. 22 AWG Hookup wire, Solder wick, and a Hot glue gun.
5. In the photo the 3x 100 Ohm resistor are in parallel which is wrong so make sure to wire them in series otherwise everything is correct.

I honestly reccomend buying the dummy battery adapter as this can be dangerous if your day isnt going well,or if you want to do it inexpensive instead of buying an expensive adapter plug, we can hack a physical connection directly out of an old, dead battery pack.

1. Crack open the casing: Carefully pry open the plastic shell of your old battery pack using a small flathead screwdriver or utility knife along its seam line. Discard the dead lithium-ion cells responsibly.
2. Isolate the PCB contacts: Look inside at the small integrated board holding the gold contact pads that touch the camera pins. Use your utility knife to physically score and cut the copper traces leading from the old internal protection ICs to the gold contacts. This prevents the old battery circuitry from interfering with your external voltage.
3. Identify polarity: Check the outside markings of the battery shell to confirm which pad is Positive (+) and which is Negative (-). Ignore any communication or temperature pins (often labeled "C" or "T").
4. Solder input pigtails: Solder a red wire directly to the back of the Positive gold contact tab, and a black wire to the Negative tab.
5. Strain relief: Pass the wires out through a small notch in the corner of the plastic housing. Fill the empty internal cavity with hot glue or epoxy to lock the wires permanently in place so they can't tear away during a shoot.

MAKE SURE YOU HAVENT DAMAGED THE PCB WHILE TAKING IT OUT BY USING YOUR MULTIMETER ON BEEP MODE TO CHECK ANY PATH BW P+ and P- as if that happens its basically a short and will ruin your electical components ; (

Step 3: Assembling the LC Filter Stage

This stage strips out high-frequency noise and ripples coming from your main 12V adapter before it ever reaches the regulator.

1. Solder your 2-pin screw terminal to the far left edge of the $2\times8\text{ cm}$ perfboard for your Vin (+) and GND (-) connections.
2. Solder the two PCB fuse clips into place directly inline with the Positive rail. Snap your 1A glass fuse into the clips.
3. Mount the 220uH Inductor (L1) inline on the positive rail.
4. Place the: 470uF capacitor (C1) across the rails before the inductor, and the 220uF capacitor (C2) across the rails after the inductor.

⚠️ Polarity Check: Ensure the silver negative stripe on both C1 and C2 points directly to the Ground rail otherwise it can blow the caps.

Step 4: Building the Custom Resistor Chains

Because standard resistors don't always match the exact mathematics needed to output a safe voltage from the LM317, we will create custom values by chaining smaller resistors together.

The R1 Voltage Bridge (242 Ohm Total)

Take one 220ohm resistor and one 22ohm resistor. Solder them end-to-end in series. This gives you exactly 242ohm. This chain will bridge the Output and Adjust pins of your LM317.

The R2 Ground Chain (1.3K Ohm Total)

Take one 1K ohm resistor and three separate 100 ohmresistors. Solder all four end-to-end in series. This creates a highly accurate 1.3k Ohm resistance chain that connects your LM317's Adjust path down to the common ground rail.

The Rsc Current limiter (upto 1A Limit, adjustable if you have accessories)

To limit our maximum output safely to 1A without burning out standard 1/4W resistors, we will split the load across 8 resistors.

1. Line up seven separate 10Ohm 1/4 watt resistors side-by-side.
2. Twist all 7 left-side legs together into one thick lead, and twist all 7 right-side legs together.
3. Solder them as a uniform "raft." This parallel combination gives you an exact resistance of 1.4 Ohm, safely spreading the power dissipation so everything runs cool.
4. or you can also use a higher wattage resistor to make soldering easier.

Step 5: Wiring the LM317 Linear Regulation Stage

The LM317 drops the filtered 12V input down to your target voltage. It is critical to install the protection diodes properly here.

1. Securely mount a small clip-on aluminum heatsink onto your LM317T before soldering it to the center of your board.
2. Solder your custom R1 Resistor Bridge directly between Pin 4 (Output) and Pin 1 (Adjust).
3. Solder your custom R2 Ground Chain from Pin 1 (Adjust) down to your GND rail. Place your 10uF capacitor (C5) in parallel right alongside this ground chain.
4. Install Diode D1: Solder a 1N4007 diode between the Input (Pin 1) and Output (Pin 4). The silver stripe (Cathode) must point toward the Input pin.
5. Install Diode D2 (Crucial): Solder a 1N4007 diode between the Adjust pin and Output pin. The silver stripe (Cathode) must point toward the Output pin.

Step 6: Wiring the Current Limiter and SCR Crowbar Protection

This final stage acts as an active electronic bodyguard for your DSLR.

1. Cut your positive power track right after the LM317's output pin and solder your 7-resistor current-limiting raft (Rsc) directly into that gap. The power must go through this raft to reach your camera otherwise it wouldnt limit current.
2. Place your 8.2V Zener Diode right after the resistor raft. Connect its non-striped end (Anode) directly to the Gate (Pin 3) of your BT151 SCR. Connect its silver-striped end (Cathode) directly to the Positive output line.
3. Mount the BT151 SCR. Connect Pin 1 (Cathode) straight to Ground, and Pin 2 (Anode / Middle) straight to the Positive Output Rail. Leave its metal back tab exposed in the air—do not let it touch any other metal or heatsinks.
4. Place your final 10uF capacitor (C4) across the output rails.

Step 7: Final Tweaks and Testing

Before hooking this up to your camera, you must perform a cold sanity check to ensure no short circuits exist.

1. Add the final filter: Solder a tiny 100nF ceramic capacitor across your final output screw terminal. This catches any remaining microscopic high-frequency processor noise right at the exit wire.
2. The Multimeter Test: Turn your multimeter to Resistance/Continuity mode. Touch your probes to the Output positive and output ground terminals.
3. If it beeps or shows O ohm, you have a bridge or a backward diode. Clear any solder bridges before proceeding.
4. Check Diode D2 again: Ensure the silver stripe is facing the LM317 Output pin.
5. Live Voltage Check: Plug your 12V wall adapter, Battery, or a usb with 12v output into the input terminal. Measure the voltage across your output screw terminals with your voltmeter. It should read a beautifully steady ~7.97V to 8.0V.
6. Connect your Dummy Battery: Screw your dummy battery pigtail leads into the output terminal, slide the dummy shell into your camera slot, and power it up! You now have an incredibly clean, stable, fully protected studio power rig.

Disclousre: AI was used to make the wiring diagram but nothing else.