Description
This custom isolated power supply is used when a time clock must control bells, buzzers, or other signaling devices without exposing the clock’s internal electronics to damaging electrical loads. It provides full electrical isolation between the clock’s low-voltage control output and the higher-power circuit that actually drives the signal devices.
Most electronic and biometric time clocks are designed to output only very small control signals—typically around 0.1 amps at 30 volts or less. Attempting to power bells or buzzers directly from these outputs can destroy the clock’s circuit board due to overload, voltage feedback, or inductive spikes. This system is engineered specifically to prevent that failure.
In operation, the clock sends only a minimal control signal (usually 12–18V at ~0.05 amps) to actuate the isolation circuitry. The bell or buzzer power is supplied independently, ensuring that no high voltage or high current can reach the clock itself.
Custom-Built Configuration
Each unit is built to match the specific clock it will be used with. Time clock manufacturers use many different signaling methods, including 12VDC, 18VAC, 30VDC, 48VDC, and others. There is no universal configuration. Depending on the application, the system may use relay isolation alone or relays combined with AC coils, DC power supplies, or reduction transformers.
Capacity & Protection
- Powers up to 2 × 24VAC buzzers
- Or up to 6 × 24VAC bells
- Or up to 10 × 110VAC bells or buzzers
- 10-amp output capacity (more than sufficient for most installations)
Installation & Build Quality
A heavy-duty 2-pole, 10-amp relay provides electrical isolation and protects the clock from feedback, surges, and wiring faults. The assembly is housed in a metal enclosure (plastic when appropriate), fully wired, labeled, assembled, and tested before shipment.
This is a complete, purpose-built solution. No sourcing parts, no trial-and-error wiring, and no risk to your time clock. It delivers reliable, synchronized bell or buzzer operation while protecting your equipment.