120 VAC & 12 dc connection
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Posts: 46,084
Does anyone know what kind of relay to use to turn on a 120 AC
appliance with a BS2? Also want to do the same in another project
with 12v DC. I know I could buy the opto kit. But that seems like
overkill for what I want to do. Thanks.
appliance with a BS2? Also want to do the same in another project
with 12v DC. I know I could buy the opto kit. But that seems like
overkill for what I want to do. Thanks.
Comments
also drive a relay coil (not directly; you'll need a transistor or suitable
buffer) and use the contacts to switch your AC. Be careful, 120 VAC bites
pretty hard.
-- Jon Williams
-- Parallax
In a message dated 12/4/02 3:51:07 PM Central Standard Time,
mike@k... writes:
> Does anyone know what kind of relay to use to turn on a 120 AC
> appliance with a BS2? Also want to do the same in another project
> with 12v DC. I know I could buy the opto kit. But that seems like
>
[noparse][[/noparse]Non-text portions of this message have been removed]
pick your 120vac device and then get it's amps.
Relays contacts have an AC amp rating, a DC amp rating and an
inductive load amp rating for motors. Motors often pull 5x running
amps when they start so the relays must handle the surge.
once you know your device and contact amp rating, find any relay you
like that has the proper connectors and size, ie: wires, plug-in or
circuit board connectors.
That relay will be available in 5 volt, 10-12 volt, 24 volt and 120
volt coils and possibly 48 volts. the lower voltages are typically
DC and the higer, 24 and above, are typically AC. I forget the
derating if you chose to power an AC relay with DC.
the electromagnet coil is all you are concerned about as regard the
Stamp. The coil is all that the electronics will ever see. Relays
totally isolate the contacts from the signal. find the voltage and
wattage of the coil and then you know what you need to drive it.
Typically a darlington will do nicely. UNL2003 has the diode to
eleminate probems with spikes as the relay opens and closes.
UNL2003 is 7 circuit and will drive 7 relays
UNL2803 will drive 8 relays.
Since the contacts on the 110 side are totally isolated from the
Stamp/transistor side you don't need optoisolators.
Dave
--- In basicstamps@y..., "byte_me60" <mike@k...> wrote:
> Does anyone know what kind of relay to use to turn on a 120 AC
> appliance with a BS2? Also want to do the same in another project
> with 12v DC. I know I could buy the opto kit. But that seems like
> overkill for what I want to do. Thanks.
Excellent advice, but I think you meant ULN2003, not UNL. I thought I would
also mention that the outputs can be paralled for greater current.
Jonathan
Original Message
From: "Dave Mucha" <davemucha@j...>
To: <basicstamps@yahoogroups.com>
Sent: Wednesday, December 04, 2002 6:51 PM
Subject: [noparse][[/noparse]basicstamps] Re: 120 VAC & 12 dc connection
> Hi,
>
> pick your 120vac device and then get it's amps.
>
> Relays contacts have an AC amp rating, a DC amp rating and an
> inductive load amp rating for motors. Motors often pull 5x running
> amps when they start so the relays must handle the surge.
>
> once you know your device and contact amp rating, find any relay you
> like that has the proper connectors and size, ie: wires, plug-in or
> circuit board connectors.
>
> That relay will be available in 5 volt, 10-12 volt, 24 volt and 120
> volt coils and possibly 48 volts. the lower voltages are typically
> DC and the higer, 24 and above, are typically AC. I forget the
> derating if you chose to power an AC relay with DC.
>
> the electromagnet coil is all you are concerned about as regard the
> Stamp. The coil is all that the electronics will ever see. Relays
> totally isolate the contacts from the signal. find the voltage and
> wattage of the coil and then you know what you need to drive it.
>
> Typically a darlington will do nicely. UNL2003 has the diode to
> eleminate probems with spikes as the relay opens and closes.
>
> UNL2003 is 7 circuit and will drive 7 relays
> UNL2803 will drive 8 relays.
>
> Since the contacts on the 110 side are totally isolated from the
> Stamp/transistor side you don't need optoisolators.
>
> Dave
>
>
> --- In basicstamps@y..., "byte_me60" <mike@k...> wrote:
> > Does anyone know what kind of relay to use to turn on a 120 AC
> > appliance with a BS2? Also want to do the same in another project
> > with 12v DC. I know I could buy the opto kit. But that seems like
> > overkill for what I want to do. Thanks.
>
>
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