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Switching Answered

Hi, I am new to electronics although I am an electrician by trade. I need to know if there is a way to switch a load electronically. It needs to switch from one load to another. I also need to know if there is a way to monitor current flow so that it switches when it hits a specified current. Thanks in advance Edd

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killerjackalope

11 years ago

You could use either relays or transistors though specifying the current isn't something I know... What's the actual project, it might help to give more details.

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eddcolekillerjackalope

Reply 11 years ago

Hi I dont want to use relays as there 15 cables to switch at the same time. It is very low current ie max 2 amps. I know I can do through relays but as i say I dont really want to. I want to be ablet to switch my computer output from one screen to another, I have looked at KVM's but just fancy building something myself.

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killerjackalopeeddcole

Reply 11 years ago

Hmm, that sounds like a simple case of switching, granted it's probably not that easy to switch fifteen contacts at once unless you find a very long switch. you could make a very cool mechanical switch in two ways, have fifteen toggles, solder a bar across all fifteen then make a simple mechanism to make it look like a big old throw switch. The other way would be to utilize the existing plugs in a way or even make your own switch by adding contacts and having it throw from one output to the other, granted it would have to be reasonably precise in the build quality or you may miss contacts. The other thing I can think of is using relays to control them from a single switch, the reason for relays is that they're isolated from the other circuit and are less likely to interfere, one minor issue is that you'd either have to power the switch via USB or a 9V battery if relays were used... You can switch to different outputs via software as well though.

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eddcolekillerjackalope

Reply 11 years ago

Thanks for the reply, I have already built a switch with relays and it works great, I just wanted to get more into electronic side rather than mechanical. Im tring to look at making the switch with a couple of transistors or something like that. I know it must be possible (obviously) but i just want to work out how.

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guyfrom7upeddcole

Reply 11 years ago

well why does it have to be current sensing?

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eddcoleguyfrom7up

Reply 11 years ago

Hi, it does not need to be current sensing. That is for another project I am looking at i.e if a current in an item goes below a set current then it will turn it off.

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Padlockeddcole

Reply 11 years ago

I know that when you turn on the flashers in a car, there is a relay that blinks at a certain speed depending on the current of the load (That's why you have to add a large resistor when switching from incandescent to LED headlights). I don't know if you could innovate it into your design, but just posting.

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gmooneddcole

Reply 11 years ago

If you only need to switch the signals, then a CMOS 4066 quad switch ic is a good choice (note: there are more modern alternatives, so search for "analog switch".)

If higher current is involved (and you don't mind higher cost and complexity), you can build your own version of the CMOS device with larger complementary MOSFET switching pairs. Larger, more capable transistors will == more current.

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eddcolegmoon

Reply 11 years ago

Thanks GMOON this may be the answer ill see if i can get a few and try this out