How to turn on/off power amp with remote

Discussion in 'Archived Threads 2001-2004' started by AlexChoi, Dec 14, 2001.

  1. AlexChoi

    AlexChoi Auditioning

    Jan 20, 1999
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    My power amp does not have any 12V trigger. Any suggest to control ON/OFF to the power ampp via remote?

    Thanks in advance

  2. Sankar

    Sankar Second Unit

    Aug 1, 1999
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    If you are handy with a soldering iron, then you can

    purchase a 20A DPDT (Double Pole Double Throw) relay (if you can find a DPST, that will work, but I could not locate one myself) with a 120V coil from any electronics store (Radio Shack also has some of these), and use the 120V switched outlet in your receiver to do the triggering.

    You will of course need a box to house this in etc as well.

    I did this recently for my AT1504 .. works perfectly and cost me about $30 including the box, led, cables etc.

    Send me email, if you need details.
  3. Wayne A. Pflughaupt

    Aug 5, 1999
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    Katy, TX
    Real Name:
    If you’re not handy with a soldering iron it will cost you a little more. Check into Adcom’s ACE-515 line conditioner. You can plug all your gear, including the amp into it. The ACE has a 120VAC trigger line that plugs into a receiver’s switched outlet. When you turn the receiver on the source components come on first, and the amp switches in 10 seconds later. On power down it works just the opposite. The amp turns off first, then 30 seconds later, after the capacitors have discharged, the rest of the gear turns off.

    The ACE-515 lists for about $200, but you can find them on e-bay for around $100.

    Happy Holidays,

    Wayne A. Pflughaupt
  4. Ken Bohn

    Ken Bohn Auditioning

    Dec 20, 1999
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    I will also be doing the same thing that Sankar suggests for a buddy of mine during the holidays. Its a simple solution to simplify the control of a system.

    You can usually find plastic 'project boxes' at electronic stores to house the components and I have seen them at Radio Shack. I am going to use a relay with a separate plug in base to simplify shopping although you can find complete relays with screw terminals on the relay case for wire connections.

  5. Sankar

    Sankar Second Unit

    Aug 1, 1999
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    Since I got a couple of requests for this, I decided to post my replies to them here:
    This is a relatively simple project that should take you about an evening to complete (once you have all the parts). From my description below, you may conclude that its complicated, but its actually much simpler than it sounds.
    First, you need to decide the maximum current you want the relay to handle. If you come up with a number under 10A, then you are in a lot of luck .. if its 15A or so, then you will need to do a little more work. The reason I say this, is because the max rated relay I could find at Radio Shack was a 10A one … catalog item # 275-217, priced at $7.99.
    If you want, say more, then you have two options
    1. use two of these 10A relays in parallel or
    2. go to the local electronics store and ask for a DPDT 20A relay with a 125VAC coil (the 125VAC coil means that it can be triggered by the AC line voltage .. a 12VDC coil will require you to drop the voltage, rectify etc etc .. a pain, in my opinion)
    I chose the second option and ended up buying a 20A DPDT relay from a local electronics parts store (Marvac electronics in Pasadena, CA) for about $18. This was a little more expensive than buying 2 Radio Shack 10A relays, but simplified the assembly process (since there was only 1 relay to mount). Whichever way you go, it should be fine (you can also check a local pool/hot tub store which also sell these items .. though they do so at a premium relative to electronic stores). Remember that if you are plugging the entire apparatus into a 15A power circuit with other components, going for a 20A relay is an overkill .. you might as well stick with the 10A relay. I have a dedicated 20A circuit for the amp, hence decided to stay at 20A all the way. Most of the time, your amp will draw less than 5A, with a few occasional surges (and most 10A relays should handle a surge to 15A with no problems). I would also check the fuse on your amp – if it is rated at 12A or less, you can comfortably stay with the 10A relay.
    If are not familiar with relays, they are basically little “switches” controlled by an electromagnet inside. When a signal voltage (120 V from the receiver in this case) is applied to the “coil”, the magnet pulls a metal plate which then makes a connection and allows a large amount of current to pass (i.e. just like a switch .. only its “automatic”). If there are 2 plates, then this is a “double pole” relay. You need 2 poles … one for the “hot” and one for the “neutral” lines of your power supply.
    To be more specific, lets label the contacts (there will be 8 of them) in a DPDT relay as A1, A2, A3, B1, B2, B3 and C1,C2.
    C1,C2 are the coil connections .. these activate the electromagnet when a voltage is applied
    When there is no voltage across C1,C2, A1 is connected to A2 and B1 is connected to B2 (and of course, A1,B1,C1 are not connected in any way).
    When a voltage is applied across C1,C2, A1 is connected to A3 and B1 is connected to B3.
    We will follow this naming convention in the wiring. Make sure that you have identified all these contact points at the outset.
    Once you have the relay(s), you will also need the following:
    (i) a 3 pin plug socket (the type you find at a local hardware store is fine .. the ones we use in the house for all plugs etc)
    (ii) a good sturdy power cable with a 3 pin plug at one end (open wire at the other) .. I picked this up also at the local electronics store from their surplus bin (the cable should be able to handle the max power of the relay)
    (iii) a regular ac cable with a 2 pin plug at one end (this
    is the one that will go to the receiver) and bare wire at the other end
    (iv) an optional 125Vac led (this is optional to show that the “juice” is flowing) .. the 125Vac rating will allow you to put it across the output directly.
    (v) a box of appropriate dimensions to house everything (relay, led, plug socket) .. get one that’s a little larger than the minimum requirements.. it will give you more space to work inside. Metal or plastic is fine.
    (vi) a couple of strain reliefs for the wires (also at the electronics store). These are little plastic things that protect the internal wiring connections if the wire is accidentally pulled from the outside of the box
    Now for the assembly:
    Mount the relay in the box (usually the relays will have slotted holes through which you can pass a small bolt and fasten with a nut. Also cut out a hole for the plug and mount that on as well (same way, using a couple of small bolts and nuts). If you got an led .. then this is the time to mount that as well. Do these all first since they determine the physical locations in the box.
    Also determine the entry points for the wires, and fix them as well (remember to leave yourself some extra length to work with)
    Single relay option:
    The 2 ends coming from the receiver will go to C1 and C2
    Next wire the hot and neutral leads from the main wire (the big one which will plug into your mains) to A1 and B1.
    Connect A3 and B3 to the hot and neutral points of the plug socket. (make sure that if A1 was connected to the wide pin of the plug, then A3 is also connected to the wide female in the socket. This will make sure that the hot and neutral are not swapped)
    Connect the ground wire coming from the mains directly to the ground terminal on the plug socket (i.e. ground is always connected).
    Leave A2 and B2 unconnected.
    Wire the optional led across A3,B3. (if you wish, you could put an extra diff colored led across A2,B2 to indicate that there is power in the wall, but none going to the amp)
    You will finally plug the other end of the wires going to C1,C2 to the switched outlet on the receiver, and plug the amp into the socket in the box. (however don't do that yet)
    How does it work ?
    When there is no voltage across C1,C2, there is no voltage across A3,B3 (however, there is 125V across A1,B1 and also across A2,B2 which are not connected to anything). When the receiver sends a voltage to C1,C2, then there is 120V across A3,B3 which is connected to the amp (and power led).
    Now that you have assembled everything, test it first using a lamp (not your amp!) ..
    a) connect the main power cable (going to A1,B1) to the wall
    b) connect a small test lamp (any table lamp will do the job) to the plug socket on the unit. The light should not come on.
    c) Plug the other cable (going to C1,C2) to another wall socket .. you should hear a click from the relay and the lamp as well as the led should come on.
    d) When you disconnect the cable (going to C1,C2), the lamp should go out (as well as the led)
    If this works as above, close everything up (make a final check to ensure that all connections are clean, insulated etc), run the test again (not your amp yet!) .. and then plug in the amp etc .. go get a beverage from the fridge and enjoy your new gadget!
    If you have 2 relays, then wire one exactly as above and connect the corresponding contacts between the 2 relays (i.e. A1 to A1, A2 to A2, etc). This will make them work in parallel
  6. Gordon C Jr

    Gordon C Jr Stunt Coordinator

    Aug 15, 2001
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    Can't you connect the plug to a switchable outlet on the back of your pre-amp? So that the amp will come on when the pre-amp is turned on?
  7. Guy Kuo

    Guy Kuo Supporting Actor

    Mar 6, 1999
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    Gordon, the type of amp being powered has a high current demand during operation and initial startup. The initial current load as the amp first turns on is very high and will overload almost any switched convenience outlet on a receiver. Even the normal operating load after startup is too high for such a convenience outlet. After all, those convenience outlets have a pitifully low wattage limit.

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