What are Relays used for

[walters]

What are Relays used for?

I seen Relays used for Switching inputs , outputs, grounds

The relays used to Isolate the grounds how do design engineers do this?

 

[walters]

I seen this Design tech. take a regular preamp and eq circuit before it had no relays and then he added like 40 or more relays to do all the switching,grounding,isolation

How do you use relays to do isolation?
i think he used relays like isolation transformer

How do you use relays to isolate the ground from circuit ground from
The lighting panel grounds to run lights from the relays them self have to have another grounding so you don't hear the clicky cheater coming up from the ground

I know to use a isolation transformer to with alot of secordary isolation
terminal to use it to seperate all the grounds

How do most most design tech modify a circuit that has No relays and
then adds alot of relays to do all the switching,grounding,isolation?

The switch on the front panel would be a DC voltage going to the relay?
and the relay would handle all the switching,grounding,isolation?

 

[barkha]

Relays are used:
=> to control a high-voltage circuit with a low-voltage signal, as in some types of modems
=> to control a high-current circuit with a low-current signal, as in the starter of an automobile
=> to detect and isolate faults on transmission and distribution lines by opening and closing circuit breakers (protection relays),
=> to isolate the controlling circuit from the controlled circuit when the two are at different potentials, for example when controlling a mains-powered device from a low-voltage switch. The latter is often applied to control office lighting as the low voltage wires are easily installed in partitions, which may be often moved as needs change. They may also be controlled by room occupancy detectors in an effort to conserve energy,
=> to perform logic functions. For example, the boolean AND function is realised by connecting relay contacts in series, the OR function by connecting contacts in parallel. Due to the failure modes of a relay compared with a semiconductor, they are widely used in safety critical logic, such as the control panels of radioactive waste handling machinery.
=> as oscillators, also called vibrators. The coil is wired in series with the normally-closed contacts. When a current is passed through the relay coil, the relay operates and opens the contacts that carry the supply current. This stops the current and causes the contacts to close again. The cycle repeats continuously, causing the relay to open and close rapidly. Vibrators are used to generate pulsed current.
=> to generate sound. A vibrator, described above, creates a buzzing sound because of the rapid oscillation of the armature. This is the basis of the electric bell ,which consists of a vibrator with a hammer attached to the armature so it can repeatedly strike a bell .