12V AC-AC Power Adapter, 1670mA (1.67A) Wall Transformer, 3-Screw Terminal Output, AC12V Linear Power Supply | AC-121S3
12V AC-AC Linear Wall Transformer — 1670mA (1.67A)
Part AC-121S3
The AC-121S3 is a wall-mount linear AC-to-AC power adapter delivering 12V AC output at 1670mA (1.67A, ~20VA) via a 3-position screw terminal block. This hardwired terminal connection makes it the ideal replacement transformer for systems that use direct wire leads instead of a standard barrel plug.
⚠️ Critical Note: This is an AC-AC adapter. It outputs alternating current (~), not DC. A device labeled 12VDC is not compatible. Verify your device power requirements before purchasing.
Technical Specifications
- Model: AC-121S3
- Input: 120V AC, 60Hz (Standard US Wall Outlet)
- Output: 12V AC at 1670mA (1.67A, ~20VA)
- Output Connector: 3-Position Screw Terminal Block
- Type: Wall-mount linear transformer (non-regulated)
Common Applications & Compatible Systems
- Alarm & Security Panels: Hardwired replacement transformer for DSC, Honeywell (Resideo), Ademco, and Napco security control panels requiring direct terminal wire inputs.
- Gate & Door Access Controllers: Powers electric gate openers, access control boards, and keypad entry systems with terminal block connections.
- Electric Strikes & Door Locks: Supplies reliable 12VAC to magnetic locks and electric strikes wired directly to control boards.
- Low-Voltage Control Equipment: Replacement transformer for commercial HVAC control modules, timers, and industrial relays requiring hardwired 12VAC up to 1.67A.
Known Cross-References & Applications
- Security Industry Standard: Direct plug-in replacement for standard 12V AC 20VA security transformers with screw terminals.
- HVAC & Access Control: Suitable for 12VAC low-voltage automation boards and door strike controllers specifying up to 20VA power capacity.
Common Replacement Compatibility
Use as a replacement only when the original transformer or equipment manual specifies 12VAC, screw terminal connections, and a current load not exceeding 1670mA (1.67A / 20VA). Confirm your device requires AC output and uses terminal connections before wiring.
Frequently Asked Questions
Q: How do I connect wires to this transformer?
A: Strip the ends of your two-conductor low-voltage wire, insert the bare leads into the outer screw terminal slots, and tighten the terminal screws securely.
Q: How do I know if my device needs AC or DC?
A: AC is indicated by the ~ symbol or the letters VAC. DC is indicated by VDC or the DC symbol (⎓). This adapter is not for DC-only devices.
Q: Why does my voltmeter show higher than 12V when tested?
A: This is an un-regulated linear transformer. Unloaded (no-load) voltage readings will naturally measure higher until connected to an active load.
Q: Does wiring order matter on the screw terminals?
A: Because AC output has no positive or negative polarity, standard 2-wire AC installations can attach to either terminal screw slot.
