replacement for relay.

[jeyes56]

is there any replacement for relay?

im thinking of using of transistors, but im not that familiar with transistor.
can a transistor act like a relay? the load is very small.

 

[ericgibbs]

is there any replacement for relay?

im thinking of using of transistors, but im not that familiar with transistor.
can a transistor act like a relay? the load is very small.

hi,
You can buy Solid State Relays, [SSR] for a range of switch voltages, operating by low voltage DC or AC

 

[aljamri]

is there any replacement for relay? .

SCR in DC and TRIAC in AC are two famous replacements of the late Relay, but your circuit has to be redesign. For direct replacement (minor changes) go for the SSR as Eric suggested.

 

[crutschow]

Do you need isolation of the relay output from the control, i.e. can they share the same ground?

 

[jeyes56]

i do need isolation of the relay output from the control, they should not share same ground.

 

[Reloadron]

is there any replacement for relay?

im thinking of using of transistors, but im not that familiar with transistor.
can a transistor act like a relay? the load is very small.

Define "very small"?

Depending on very small use an opto coupler to turn a transistor on or if very small is something like a few mA maybe just the opto coupler.

Ron

 

[jeyes56]

ok,, here is the load,, i need to short the button of a cellphone (number 9), that's why i used a relay,, is there any replacement for the relay? i need to isolate the load from control..

 

[SABorn]

As Ron said use an opto coupler.

Pete.

 

[KeepItSimpleStupid]

How about an Opto FET?

 

[jeyes56]

optocoupler is like a LED and Photo Transistor, it uses a voltage source in its load,, but how do i connect the photo transistor part to my button 9 in my cellphone?

 

[KeepItSimpleStupid]

Here is one of my favorite interface devices: https://www.newark.com/excelitas-tech/vtl5c1/optocoupler-resistor-2500vrms/dp/43F885 It uses a FET, not a transistor and it uses wires. It is kinda big.

 

[Reloadron]

optocoupler is like a LED and Photo Transistor, it uses a voltage source in its load,, but how do i connect the photo transistor part to my button 9 in my cellphone?

I am traveling so I don't have my drawing software but the photo transistor side should have a collector and emitter. Measure across the open button. One side is likely common. The other side should show a voltage. The phone pad likely has internal pull up. Emitter to common and the collector to voltage side of the button. That assumes a NPN photo transistor (opto coupler).

Generally you want to know all the parameters before you choose a photo transistor.

Ron

 

[jeyes56]

ok, so the number 9 button on cellphone have a voltage across them w/c is enough to power activate the transistor?

if that so, i may use a transistor itself, but they should share the same ground.

but i actually don't know if my project can share the same ground from control to load.

the control is an 555 monoastable timer powered by 9v, (but i may lower it to 5v when i changed my relay). the load is that on cellphone button.
is it ok to have a same ground if i use a transistor? not an opto coupler.

 

[jeyes56]

since the previous suggestions are for isolated load from control, w/c is not sharing the same ground,
is there any replacement for relay if it could share the ground from collector to load?

 

[Reloadron]

If you want isolation for the switching use an opto coupler, if isolation is not required, use a transistor. I don't know all the variables so I can't make a good suggestion.

Ron

 

[crutschow]

The safest is just use an opto isolator. That way there's no possibility of a problem by trying to use a common ground between your 555 circuit and the cellphone.