warren@ihlpf.ATT.COM (Montgomery) (01/30/89)
I am looking for a stunt box that will switch my stereo receiver on according to whether or not my turntable is running. This strikes me as a basic and common need, and while I think I could design a circuit to do this I can't believe that I can't buy a better one, or at least get ahold of plans for one. Basically what I want is something that will sense when current is drawn through one AC outlet without significantly degrading the power available, and control a second outlet according to whether or not power is being drawn. I'd also like a control switch allowing the second outlet to be always on, always off, or switched according to the first. I've poked around in a couple of stereo stores but haven't found anything like this, and as I said while I suspect I could build such a gadget I suspect I could buy a better one. Anyone have any suggestions as to what to look for or ideas for building such a gadget? -- Warren Montgomery ihlpf!warren
uchuck@ecsvax.uncecs.edu (Charles Bennett) (01/31/89)
Such devices are available through microcomputer supply and accessory
houses. INMAC comes to mind. My advice, however, is if its solid state
- leave it on all the time; if it isn't turn it on 10 minutes prior to
a listening session.
--
-Chuck Bennett- UNC - Chapel Hill
919-966-1134
uchuck@ecsvax.UUCP
uchuck@unc.BITNETsmadi@rlgvax.UUCP (Smadi Paradise) (01/31/89)
warren@ihlpf.ATT.COM (Montgomery) writes: >I am looking for a stunt box that will switch my stereo receiver on >according to whether or not my turntable is running. Here's a ``quick and dirty'' one: neutral--------------------------------------------- | | control (phono) load (amp) | | | ___ | /\/ T1 | --- | /| | R1 / | |________/\/\/\_/ | | | | v _ | - ^ | D1-D4 v _ | - ^ | | | | live------------------------------------------------ R1 100 ohm (?) D1-D4 1N4001 T1 Triac, sensitive gate, > 2 * load current, 200V. Load voltage is somewhat dirty sine wave; an .1uF/200V capacitor across the triac is recommended. Phono current should be < .7A AC. Enjoy! On (just a guest here) Paradise
dmt@ptsfa.PacBell.COM (Dave Turner) (02/01/89)
In article <7485@ihlpf.ATT.COM> warren@ihlpf.ATT.COM (Montgomery) writes: >I am looking for a stunt box that will switch my stereo receiver on >according to whether or not my turntable is running. This strikes Both Radio-Shack and Heathkit sell them. I don't have Heath's catalog handy but theirs is listed in both the stereo and ham sections. Check RS's Auto-Power Controller 26-1396 $69.95. -- Dave Turner 415/542-1299 {att,bellcore,sun,ames,pyramid}!pacbell!dmt
nts0699@dsacg1.UUCP (Gene McManus) (02/01/89)
From article <7485@ihlpf.ATT.COM>, by warren@ihlpf.ATT.COM (Montgomery): > I am looking for a stunt box that will switch my stereo receiver on > according to whether or not my turntable is running. This strikes [ stuff deleted ] > -- > > Warren Montgomery ihlpf!warren Heathkit sold these gadgets a few years back. I don't have a current catalog, but I think is was in the last one I got (a year ago, maybe). Fairly pricy, as I recall..$80 maybe. Gene Gene McManus @ Defense Logistics Agency Systems Automation Center, Columbus, OH 43215 (614) 238-9403, Autovon 850- UUCP: {uunet!gould,cbosgd!osu-cis}!dsacg1!gmcmanus The views expressed are my own, not those of The Agency, or Dept. of Defense
todd@ivucsb.UUCP (Todd Day) (02/01/89)
In article <7485@ihlpf.ATT.COM> warren@ihlpf.ATT.COM (Montgomery) writes:
~I am looking for a stunt box that will switch my stereo receiver on
~according to whether or not my turntable is running.
Radio Shack sells such a beast. It is a multi-outlet strip that trips
on one of the plugs.
Todd Day | ..!apple!comdesign!ivucsb!todd | todd@ivucsb.UUCPliber@darth.UUCP (Eric Liber) (02/01/89)
> I suspect I could buy a better one. Anyone have any suggestions as > to what to look for or ideas for building such a gadget? > > -- > > Warren Montgomery ihlpf!warren Radio Shack and Heath Kit both sell "intelligent" power strips such as you mention. They cost about $49.95 at last look. Also within the last year there was an article in either Modern Electronics or Hobby Electronics that described a circuit to accomplish this feat. It was somewhat moer complex than the circuit that was posted by someone here that used a Triac but had the advantage of requiring somewhat lower current from the control circuit. If you can't find the article and want to build one of these give me a call at : 412-374-5311 (work 8:00 am to 4:00 pm est m-f) or 412-367-7308 (home most other times) and i will copy the article for you. eric (the red baron) liber
dave@onfcanim.UUCP (Dave Martindale) (02/12/89)
In article <4674@ptsfa.PacBell.COM> dmt@ptsfa.PacBell.COM (Dave Turner) writes: >In article <7485@ihlpf.ATT.COM> warren@ihlpf.ATT.COM (Montgomery) writes: >>I am looking for a stunt box that will switch my stereo receiver on >>according to whether or not my turntable is running. This strikes > >Both Radio-Shack and Heathkit sell them. >I don't have Heath's catalog handy but theirs is listed in both the >stereo and ham sections. > >Check RS's Auto-Power Controller 26-1396 $69.95. The Heath version is GD-1495 for $59.95 in the winter '88 catalogue. It's a kit. The Heath box is not available in Canada (something about not passing CSA) and I can't find the Radio Shack one in their catalogue either. A couple of years ago, I decided I needed a box like this, and with no apparent commercial sources of them (the Heath didn't appear until later), I designed one for myself: The heart of the box is a commercial solid-state relay. The input is 2-32V DC across about a 1 Kohm load, and is optically isolated from the output circuit. The output can be rated at 10, 25, or more amps, depending on your budget, and can handle subtantial surges above that - good for me, since the main switched device was to be an audio power amplifier with big input capacitors. It needs a heat sink, but the metal mounting plate is isolated from both input and output circuits. I put a full-wave bridge rectifier in series with the "control" outlet on the box. The DC outputs of the bridge are connected to the solid-state relay inputs. Four 6-amp ordinary rectifier diodes are connected in a series string, and the string is connected across the SSR input so it will be forward-biased. Whenever the "control" device (in my case the preamp) is turned on, it draws current through the bridge, which supplies current and voltage to the SSR input. The voltage across the SSR rises to about 2.4 V, and then the diode chain conducts, carrying almost all of the load current. I believe there is also a capacitor across the SSR input to provide reliable SSR triggering even when the "control" load is not resistive. There is a 1A fuse in series with all this, so excessively large loads will eventually blow the fuse. The voltage "lost" across the bridge and diode string is about 4 or 5 V, not enough to bother most loads. The bridge must be rated to block the full AC line peak reverse voltage plus some extra, and must carry the full "control" load current. The voltage-limiting diodes are never reverse-biased, so their voltage rating is unimportant, but they need to be rated for the full control load current with a good margin of safety. These diodes are protecting the input of the SSR (the only expensive part), and in case of a current surge you would like the bridge to fail before the voltage-limiting string. That's why I used 4 forward-biased rectifier diodes instead of a single Zener - their surge current rating is something like 400A, much higher than an equivalent Zener. The advantage of using this sort of circuit directly in series with the control output is that it is very sensitive - it takes only a few mA of load current to trigger the box. The disadvantage is that the full control load current goes through these diodes, so they have to be heavy, and you can't use a really large load on the control outlet, so the box isn't as general-purpose as I'd like. There's also the voltage drop across the bridge. You could also sense the control load by using a step-up transformer made with 14-gauge wire for the primary. However, I have no experience in transformer design, and I'm not sure how you would go about designing it to work reliably over the 10 mA - 15 A range of load currents while driving the SSR directly. And adding amplification means power supplies, another headache. Does anyone know how the Heath or Radio Shack units sense the load current?
jim@trsvax.UUCP (02/15/89)
It is available from Radio Shack (cat #61-2781 $49.95 US) it is on page 140 of catalog 432 (1989). The device has six outlets: one for the controllingh device, four switched, and one unswitched. James T. Wyatt UUCP:decvax!microsoft!trsvax!rwsys!jim KA5VJL