Hey all, New to circuitry

Ive managed to identify the following components

• Relays
• LEDs
• 3 pin terminal screw blocks
• Resistors

However
In b), what are the two cylindrical drums? Capacitors? what is there purpose as they arnt present on the other five boards
In c), what is the named type of the yellow terminal block called?
In d), Just above the relays, sitting horizontally, are they parts labelled R1, R2, R3, resistors, if so why are these needed?
In d,e,f) what are both the bigger and smaller square/rectangular blocks, and what is there purpose?

 

In b), what are the two cylindrical drums? Capacitors? what is there purpose as they arnt present on the other five boards
In c), what is the named type of the yellow terminal block called?

d-f; lost interest.

 

thanks dl324, i assume the bridge rectifier is present because its the only relay board that takes both DC and AC Input?

as for jumper... thats sounds generic, trying to find its housing name(example XT30,60,90 / pp15,30,45)

Looks similar to Harwin headers... but can only see 1 "terminal"
https://www.mouser.co.uk/ProductDetail/Harwin/M7581-05?qs=ulE8k0yEMYZxt3PTX8/45Q==&mgh=1&vip=1

 

i assume the bridge rectifier is present because its the only relay board that takes both DC and AC Input?

Using a bridge rectifier allows the input to be polarity independent and support AC or DC.

as for jumper... thats sounds generic

That's because they're generic parts. Shorting blocks, jumpers, etc.

From Jameco: