Random circuits

Here are some of over 800 projects from our free circuit diagrams database. For more, try browsing categories menu on the left.

Tube Power amp Dynaco ST-70

Tube Power amp. Dynaco ST-70... [read more]

IR Remote Control Tester

IR Remote Control Tester... [read more]

Amplified Ear

This circuit, connected with 32 Ohms impedance mini-earphones, can detect very remote sounds. Useful for theatre, cinema and lecture goers: every word will be clearly heard.... [read more]

A Regularly Repeating Interval Timer

This circuit has an adjustable output timer that will re-trigger at regular intervals. The output period can be anything from a fraction of a second to half-an-hour or more - and it can be made to recur at regular intervals of anything from seconds to days and beyond.... [read more]

Multicolor HD LED

Most PC enclosures provide only a single LED to indicate hard disk access, with the LED being connected to the motherboard via a two-pin connector. However, this LED only works with IDE drives, and if a SCSI disk controller is fitted, its activity will not be visibly noticeable. This small circuit remedies that problem using a multicolour LED. The activity LED for the IDE interface is usually driven by a connected device via one or more open-collector stages.... [read more]

Mains Operated LED Circuit Schematic

Here is a simple and powerful LED circuit that can be operated directly from the AC 100 volt to AC 230 Volts mains supply. The circuit can be used as mains power locator or night lamp etc.. The resistor R1,R2 and capacitor C1 provides necessary current limiting. The circuit is sufficiently immune against voltage spikes and surges.... [read more]