A
Abstract Dissonance
- Jan 1, 1970
- 0
For my project I have to switch analog signals in certain combinations. I
was going to use reed relays since I prefer to have the least amount of
degredation of the signals from the circuit(which consists basicaly of turn
on and off the signals in different combinations). I have several questions
about relays though that I need to be aware.
1. Do relays retain there state with no power? At first I thought that one
had to switch on the relay by continuously supplying power(i.e. the
"contacts" wouldn't "snap" into an on or off state and say there without
power)... but I'm not sure about this since I've seen some "on" current and
"off" current in the data sheets of some relays. If it is true that one can
just pulse the contacts with the appropriate current to turn them off and
turn them on this would mean that they would require no power when not being
switched?(which is what I would like for my project since it minimizes the
power used since I don't switch very often(few times a min at most)).
2. How do analog switches that use semiconductors compare to relays? I can
get 4x's the number of switches at about the same price as one relay(and I
will be using about 30 relays). Obviously the analog switches have to be
continuously powered which is a drawback but the main thing I'm worried
about is how they will affect the signal. Unfortunately I can't seem to
find any data on that aspect for the relays or analog switches.
3. I will be using some simple microcontroller to control the relays but I
figure that they probably can't supply enough current to the realys to
switch them... I guess I have to read the data sheets and figure out if they
can or not and if they can't I will have to use a transistor to control the
relays?
4. Whats the difference between voltage and currents sensing relays? I
thought all relays needed current to switch? Hence is it just a matter of
how much(i.e., "current sensing" requires a much larger current and voltage
sensing requires a little?)?
5. The only relays I can find seem to come 1 per IC. Is it possible to find
ones that are like spdt(but they alternate so one switches off when the
other switches on)? or even more like how one can get quad analog switches
but instead get quad reed relays(or whatever).
and the last question
6. Where is a good site to buy components from? Right now I've been looking
at Jameco and Newark but Jameco is pretty expensive and as few products but
is easy to navigate and search yet Newark is cheaper and has tons of stuff
but can be very confusing at times on what they are selling and where its
located.
Thanks for any help,
AD
was going to use reed relays since I prefer to have the least amount of
degredation of the signals from the circuit(which consists basicaly of turn
on and off the signals in different combinations). I have several questions
about relays though that I need to be aware.
1. Do relays retain there state with no power? At first I thought that one
had to switch on the relay by continuously supplying power(i.e. the
"contacts" wouldn't "snap" into an on or off state and say there without
power)... but I'm not sure about this since I've seen some "on" current and
"off" current in the data sheets of some relays. If it is true that one can
just pulse the contacts with the appropriate current to turn them off and
turn them on this would mean that they would require no power when not being
switched?(which is what I would like for my project since it minimizes the
power used since I don't switch very often(few times a min at most)).
2. How do analog switches that use semiconductors compare to relays? I can
get 4x's the number of switches at about the same price as one relay(and I
will be using about 30 relays). Obviously the analog switches have to be
continuously powered which is a drawback but the main thing I'm worried
about is how they will affect the signal. Unfortunately I can't seem to
find any data on that aspect for the relays or analog switches.
3. I will be using some simple microcontroller to control the relays but I
figure that they probably can't supply enough current to the realys to
switch them... I guess I have to read the data sheets and figure out if they
can or not and if they can't I will have to use a transistor to control the
relays?
4. Whats the difference between voltage and currents sensing relays? I
thought all relays needed current to switch? Hence is it just a matter of
how much(i.e., "current sensing" requires a much larger current and voltage
sensing requires a little?)?
5. The only relays I can find seem to come 1 per IC. Is it possible to find
ones that are like spdt(but they alternate so one switches off when the
other switches on)? or even more like how one can get quad analog switches
but instead get quad reed relays(or whatever).
and the last question
6. Where is a good site to buy components from? Right now I've been looking
at Jameco and Newark but Jameco is pretty expensive and as few products but
is easy to navigate and search yet Newark is cheaper and has tons of stuff
but can be very confusing at times on what they are selling and where its
located.
Thanks for any help,
AD