FAQ
TL;DR: Power all 12 devices in parallel from one regulated 12 V supply; total draw ≈ 2.1 A, and “There is no need to regulate amperage.” [Elektroda, Chuck Sydlo, post #21664356]
Why it matters: This helps makers and security installers power multiple 12 V loads safely without a tangle of wall warts.
- Total load: 6× cameras at 150 mA + 6× LCDs at 200 mA = ~2.1 A at 12 V. [Elektroda, Chuck Sydlo, post #21664356]
- Allow extra headroom for cable runs; choose ≥2.5 A if wires are long. [Elektroda, Chuck Sydlo, post #21664356]
- Prefer regulated 12 V supplies; unregulated “wall warts” rise above 12 V at light load. [Elektroda, Steve Lawson, post #21664360]
- Conservative design adds ~50% margin; one ~50 W, 12 V supply simplifies wiring. [Elektroda, Earl Albin, post #21664355]
- For resilience, split into two circuits so one fault doesn’t drop everything. [Elektroda, Chuck Sydlo, post #21664356]
Quick Facts
- Total load: 6× cameras at 150 mA + 6× LCDs at 200 mA = ~2.1 A at 12 V. [Elektroda, Chuck Sydlo, post #21664356]
- Allow extra headroom for cable runs; choose ≥2.5 A if wires are long. [Elektroda, Chuck Sydlo, post #21664356]
- Prefer regulated 12 V supplies; unregulated “wall warts” rise above 12 V at light load. [Elektroda, Steve Lawson, post #21664360]
- Conservative design adds ~50% margin; one ~50 W, 12 V supply simplifies wiring. [Elektroda, Earl Albin, post #21664355]
- For resilience, split into two circuits so one fault doesn’t drop everything. [Elektroda, Chuck Sydlo, post #21664356]
Can I power six 12 V cameras and six 12 V LCDs from one adapter?
Yes. Wire all devices in parallel to a single 12 V source. Ensure the supply’s current rating exceeds the combined load. The calculated draw is about 2.1 A. Choose a higher‑rated supply for reliability and voltage drop tolerance. “There is no need to regulate amperage.” [Elektroda, Chuck Sydlo, post #21664356]
How much current do I need in total at 12 V?
Add currents: six cameras at 150 mA (900 mA) plus six LCDs at 200 mA (1,200 mA). Total ≈ 2,100 mA, or 2.1 A. Select a supply rated above this number so it runs cool and handles cable losses. [Elektroda, Chuck Sydlo, post #21664356]
Do I need to limit or regulate current per camera or LCD?
No. Each device draws only what it needs at the correct voltage. With a 12 V source, current flow is set by each load. You do not add series resistors or current regulators for these devices. Oversizing the supply is acceptable. [Elektroda, Chuck Sydlo, post #21664356]
Should I use a regulated or unregulated 12 V supply?
Use a regulated supply. Many wall transformers output far above 12 V at light or no load, which can stress electronics. A regulated adapter maintains 12 V across typical loads, protecting your cameras and LCDs. [Elektroda, Steve Lawson, post #21664360]
Why does my 12 V wall wart read 15–18 V with nothing connected?
That’s normal for unregulated adapters. Measured examples showed 15.3 V (rated 12 V/200 mA) and 17.4 V (rated 12 V/700 mA) at open circuit. Voltage drops toward 12 V only under the rated load. Sensitive gear may not tolerate that surge. [Elektroda, Steve Lawson, post #21664364]
How much safety margin should I choose for the power supply?
Add a conservative margin so the adapter runs cool and lasts. A 50% cushion is a solid target. For many 12 V systems with multiple loads, a single ~50 W supply reduces clutter and increases reliability. [Elektroda, Earl Albin, post #21664355]
Will 10–15 ft cable runs cause problems at 12 V?
Yes, long thin wires add resistance and create voltage drop. That drop can cause low‑voltage behavior on distant cameras. Choose a larger current supply and use thicker cable or shorter runs to minimize losses. [Elektroda, Chuck Sydlo, post #21664356]
Is it okay to oversize the adapter, like using 10 A at 12 V?
Yes. A higher current rating is fine because devices draw only what they need. “If you find a supply that is 10 amps… don’t hesitate to use it.” Ensure correct voltage and proper wiring. [Elektroda, Chuck Sydlo, post #21664356]
How can I improve uptime if one device fails or someone cuts power?
Split the system into two parallel groups with separate supplies. That way, a single failure or cut disables only part of the system. Overlapping camera views add evidence even if one group goes down. [Elektroda, Chuck Sydlo, post #21664356]
What is a “wall wart”?
A wall wart is a plug‑in AC‑to‑DC adapter. Some are unregulated and output higher than their label at light load. Prefer regulated types for electronics like cameras and LCDs. [Elektroda, Steve Lawson, post #21664360]
What is an LM7812, and should I put one on each feed?
LM7812 is a linear 12 V regulator. A robust build can use a central supply with six fused, individually regulated outputs for isolation. This limits a fault on one line from dragging down others. [Elektroda, Mark Harrington, post #21664365]
How do I wire twelve 12 V devices in parallel safely?
- Use a regulated 12 V supply sized above 2.1 A.
- Distribute +12 V and ground to each device from a common terminal block.
- Keep runs short or use thicker wire to reduce voltage drop.
[Elektroda, Chuck Sydlo, post #21664356]
What failure modes should I plan for?
A device with an internal fault can overdraw current and pull the supply down, dropping all units. Per‑branch fusing and isolated feeds reduce this risk. Splitting into two supplies raises resilience. [Elektroda, Mark Harrington, post #21664365]
Does this approach suit interactive installations with short runs (~15 ft)?
Yes. With ~15 ft runs, a 2.5 A or larger regulated 12 V adapter simplifies wiring and keeps voltage stable. This matches practical feedback from similar interactive camera setups. [Elektroda, giffen Ott, post #21664358]
Do I need individual fuses on each camera/LCD feed?
Individual fuses or resettable polyfuses per branch are good practice. They localize faults and prevent one failure from shutting everything down. Combine with a sturdy central 12 V supply. [Elektroda, Mark Harrington, post #21664365]
