---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 03/27/15: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:08 AM - Relays (Larry Rosen) 2. 09:45 AM - Re: Relays (Ralph E. Capen) 3. 10:15 AM - Re: Relays (Tim Andres) 4. 11:08 AM - Re: Relays (C&K) 5. 02:26 PM - Re: Relays (Eric Page) 6. 03:04 PM - Re: Relays (Larry Rosen) 7. 08:14 PM - Re: Relays (Bob McCallum) 8. 09:31 PM - Re: Relays (Larry Rosen) ________________________________ Message 1 _____________________________________ Time: 08:08:32 AM PST US From: Larry Rosen Subject: AeroElectric-List: Relays I need some help from the experts. Digi-key has over 13,000 different power relays over 2 amps, and selecting one, for a novice like me, is a daunting task. The relay is for the e-bus battery feed on a 14 volt system. The load is currently 12 amps, but I have been challenged to better define my electrical design objects and possibly reduce the load down to 8 amps. I don't think that will change the relay selection if I were to use a design of 5-20 amps. I selected TE Connectivity 1432793-1 Automotive relay SPDT 30A 12V. Here is the link It is non latching with a diode across the coil. Some of the specs, however, have me confused. The Coil voltage is 12VDC but the Switching voltage is 14 VDC - Nom. Is this an issue? Also the Turn On Voltage (Max) is 7.8 VDC and Turn Off Voltage (Min) 1.2 Volts. Does this mean that the coil requires 7.8 volts to latch and it will un-latch if voltage drops below 1.2 volts? I see that most of the automotive relays have high ohm resistors across the coil, or nothing across the coil. When would you select a resistor, diode or nothing? I have another need for a relay in my airplane. My EFIS remote annunciation mute requires a contact to be close via 2 terminals via a momentary switch. The vendor does not specify a current requirement for the switch, and when I contacted them they said any switch would work is is a fraction of an amp. I would mute the EFIS with one of the buttons on my control stick, however my control stick only has a common ground, so all switches close to ground. This would not work for the remote mute. Is there any reason why a relay wouldn't work? Would the relay above work? It probably is not the best choice, but it is only $4 and it would make for common spare parts, so if it would work it could be my 'best' choice. Larry RV-10 Builder ________________________________ Message 2 _____________________________________ Time: 09:45:39 AM PST US Subject: RE: AeroElectric-List: Relays From: "Ralph E. Capen" SSBoYXZlIHNpbWlsYXIgaW5zdGFsbGVkIGluIG15IDZBLiDCoFRoYXQgcmVsYXkgd2lsbCB3b3Jr IGZvciBib3RoIGFwcGxpY2F0aW9ucy4gwqBCZSBjYXJlZnVsIGFib3V0IHRoZSByZWxheSBhY3Rp dmF0aW9uIGNpcmN1aXQtZ3JvdW5kIHRoZSBjb3JyZWN0IHNpZGUuCgoKU2VudCBmcm9tIG15IFZl cml6b24gV2lyZWxlc3MgNEcgTFRFIHNtYXJ0cGhvbmUKCjxkaXY+LS0tLS0tLS0gT3JpZ2luYWwg bWVzc2FnZSAtLS0tLS0tLTwvZGl2PjxkaXY+RnJvbTogTGFycnkgUm9zZW4gPG4yMDVlbkBnbWFp bC5jb20+IDwvZGl2PjxkaXY+RGF0ZTowMy8yNy8yMDE1ICAwOTowNiAgKEdNVC0wNzowMCkgPC9k aXY+PGRpdj5UbzogYWVyb2VsZWN0cmljLWxpc3RAbWF0cm9uaWNzLmNvbSA8L2Rpdj48ZGl2PlN1 YmplY3Q6IEFlcm9FbGVjdHJpYy1MaXN0OiBSZWxheXMgPC9kaXY+PGRpdj4KPC9kaXY+LS0+IEFl cm9FbGVjdHJpYy1MaXN0IG1lc3NhZ2UgcG9zdGVkIGJ5OiBMYXJyeSBSb3NlbiA8bjIwNWVuQGdt YWlsLmNvbT4KCkkgbmVlZCBzb21lIGhlbHAgZnJvbSB0aGUgZXhwZXJ0cy4gIERpZ2kta2V5IGhh cyBvdmVyIDEzLDAwMCBkaWZmZXJlbnQgCnBvd2VyIHJlbGF5cyBvdmVyIDIgYW1wcywgYW5kIHNl bGVjdGluZyBvbmUsIGZvciBhIG5vdmljZSBsaWtlIG1lLCBpcyBhIApkYXVudGluZyB0YXNrLgoK VGhlIHJlbGF5IGlzIGZvciB0aGUgZS1idXMgYmF0dGVyeSBmZWVkIG9uIGEgMTQgdm9sdCBzeXN0 ZW0uICBUaGUgbG9hZCAKaXMgY3VycmVudGx5IDEyIGFtcHMsIGJ1dCBJIGhhdmUgYmVlbiBjaGFs bGVuZ2VkIHRvIGJldHRlciBkZWZpbmUgbXkgCmVsZWN0cmljYWwgZGVzaWduIG9iamVjdHMgYW5k IHBvc3NpYmx5IHJlZHVjZSB0aGUgbG9hZCBkb3duIHRvIDggYW1wcy4gIApJIGRvbid0IHRoaW5r IHRoYXQgd2lsbCBjaGFuZ2UgdGhlIHJlbGF5IHNlbGVjdGlvbiBpZiBJIHdlcmUgdG8gdXNlIGEg CmRlc2lnbiBvZiA1LTIwIGFtcHMuCgpJIHNlbGVjdGVkIFRFIENvbm5lY3Rpdml0eSAxNDMyNzkz LTEgQXV0b21vdGl2ZSByZWxheSBTUERUIDMwQSAxMlYuIEhlcmUgCmlzIHRoZSBsaW5rIAo8aHR0 cDovL3d3dy5kaWdpa2V5LmNvbS9wcm9kdWN0LWRldGFpbC9lbi8xNDMyNzkzLTEvUEIxNzczLU5E LzEyMzY4NDM+CgpJdCBpcyBub24gbGF0Y2hpbmcgd2l0aCBhIGRpb2RlIGFjcm9zcyB0aGUgY29p bC4gIFNvbWUgb2YgdGhlIHNwZWNzLCAKaG93ZXZlciwgaGF2ZSBtZSBjb25mdXNlZC4KVGhlIENv aWwgdm9sdGFnZSBpcyAxMlZEQyBidXQgdGhlIFN3aXRjaGluZyB2b2x0YWdlIGlzIDE0IFZEQyAt IE5vbS4gIElzIAp0aGlzIGFuIGlzc3VlPwpBbHNvIHRoZSBUdXJuIE9uIFZvbHRhZ2UgKE1heCkg aXMgNy44IFZEQyBhbmQgVHVybiBPZmYgVm9sdGFnZSAoTWluKSAxLjIgClZvbHRzLiAgRG9lcyB0 aGlzIG1lYW4gdGhhdCB0aGUgY29pbCByZXF1aXJlcyA3Ljggdm9sdHMgdG8gbGF0Y2ggYW5kIGl0 IAp3aWxsIHVuLWxhdGNoIGlmIHZvbHRhZ2UgZHJvcHMgYmVsb3cgMS4yIHZvbHRzPwoKSSBzZWUg dGhhdCBtb3N0IG9mIHRoZSBhdXRvbW90aXZlIHJlbGF5cyBoYXZlIGhpZ2ggb2htIHJlc2lzdG9y cyBhY3Jvc3MgCnRoZSBjb2lsLCBvciBub3RoaW5nIGFjcm9zcyB0aGUgY29pbC4gIFdoZW4gd291 bGQgeW91IHNlbGVjdCBhIHJlc2lzdG9yLCAKZGlvZGUgb3Igbm90aGluZz8KCkkgaGF2ZSBhbm90 aGVyIG5lZWQgZm9yIGEgcmVsYXkgaW4gbXkgYWlycGxhbmUuICBNeSBFRklTIHJlbW90ZSAKYW5u dW5jaWF0aW9uIG11dGUgcmVxdWlyZXMgYSBjb250YWN0IHRvIGJlIGNsb3NlIHZpYSAyIHRlcm1p bmFscyB2aWEgYSAKbW9tZW50YXJ5IHN3aXRjaC4gIFRoZSB2ZW5kb3IgZG9lcyBub3Qgc3BlY2lm eSBhIGN1cnJlbnQgcmVxdWlyZW1lbnQgZm9yIAp0aGUgc3dpdGNoLCBhbmQgd2hlbiBJIGNvbnRh Y3RlZCB0aGVtIHRoZXkgc2FpZCBhbnkgc3dpdGNoIHdvdWxkIHdvcmsgaXMgCmlzIGEgZnJhY3Rp b24gb2YgYW4gYW1wLiAgSSB3b3VsZCBtdXRlIHRoZSBFRklTIHdpdGggb25lIG9mIHRoZSBidXR0 b25zIApvbiBteSBjb250cm9sIHN0aWNrLCBob3dldmVyIG15IGNvbnRyb2wgc3RpY2sgb25seSBo YXMgYSBjb21tb24gZ3JvdW5kLCAKc28gYWxsIHN3aXRjaGVzIGNsb3NlIHRvIGdyb3VuZC4gVGhp cyB3b3VsZCBub3Qgd29yayBmb3IgdGhlIHJlbW90ZSBtdXRlLgpJcyB0aGVyZSBhbnkgcmVhc29u IHdoeSBhIHJlbGF5IHdvdWxkbid0IHdvcms/CldvdWxkIHRoZSByZWxheSBhYm92ZSB3b3JrPyAg SXQgcHJvYmFibHkgaXMgbm90IHRoZSBiZXN0IGNob2ljZSwgYnV0IGl0IAppcyBvbmx5ICQ0IGFu ZCBpdCB3b3VsZCBtYWtlIGZvciBjb21tb24gc3BhcmUgcGFydHMsIHNvIGlmIGl0IHdvdWxkIHdv cmsgCml0IGNvdWxkIGJlIG15ICdiZXN0JyBjaG9pY2UuCgpMYXJyeQpSVi0xMCBCdWlsZGVyCgpf LT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PQpfLT0gICAgICAgICAgLSBUaGUgQWVyb0VsZWN0cmljLUxpc3QgRW1haWwgRm9ydW0gLQpf LT0gVXNlIHRoZSBNYXRyb25pY3MgTGlzdCBGZWF0dXJlcyBOYXZpZ2F0b3IgdG8gYnJvd3NlCl8t PSB0aGUgbWFueSBMaXN0IHV0aWxpdGllcyBzdWNoIGFzIExpc3QgVW4vU3Vic2NyaXB0aW9uLApf LT0gQXJjaGl2ZSBTZWFyY2ggJiBEb3dubG9hZCwgNy1EYXkgQnJvd3NlLCBDaGF0LCBGQVEsCl8t PSBQaG90b3NoYXJlLCBhbmQgbXVjaCBtdWNoIG1vcmU6Cl8tPQpfLT0gICAtLT4gaHR0cDovL3d3 dy5tYXRyb25pY3MuY29tL05hdmlnYXRvcj9BZXJvRWxlY3RyaWMtTGlzdApfLT0KXy09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT0KXy09 ICAgICAgICAgICAgICAgLSBNQVRST05JQ1MgV0VCIEZPUlVNUyAtCl8tPSBTYW1lIGdyZWF0IGNv bnRlbnQgYWxzbyBhdmFpbGFibGUgdmlhIHRoZSBXZWIgRm9ydW1zIQpfLT0KXy09ICAgLS0+IGh0 dHA6Ly9mb3J1bXMubWF0cm9uaWNzLmNvbQpfLT0KXy09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT0KXy09ICAgICAgICAgICAgIC0gTGlz dCBDb250cmlidXRpb24gV2ViIFNpdGUgLQpfLT0gIFRoYW5rIHlvdSBmb3IgeW91ciBnZW5lcm91 cyBzdXBwb3J0IQpfLT0gICAgICAgICAgICAgICAgICAgICAgICAgICAgICAtTWF0dCBEcmFsbGUs IExpc3QgQWRtaW4uCl8tPSAgIC0tPiBodHRwOi8vd3d3Lm1hdHJvbmljcy5jb20vY29udHJpYnV0 aW9uCl8tPT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09PT09 PT09PT09PT09CgoKCg= ________________________________ Message 3 _____________________________________ Time: 10:15:38 AM PST US From: Tim Andres Subject: Re: AeroElectric-List: Relays And you can pick up that relay or this one: http://www.bandc.biz/spdtsealedrelay12v40a.aspx at any NAPA store, they're pretty common. But there must be a better way to control the EFIS, using a relay for that f unction doesn't seem very elegant. What control stick is it? Tim > On Mar 27, 2015, at 9:44 AM, Ralph E. Capen wrote: > > I have similar installed in my 6A. That relay will work for both applicat ions. Be careful about the relay activation circuit-ground the correct side .. > > > Sent from my Verizon Wireless 4G LTE smartphone > > > -------- Original message -------- > From: Larry Rosen > Date:03/27/2015 09:06 (GMT-07:00) > To: aeroelectric-list@matronics.com > Subject: AeroElectric-List: Relays > > > I need some help from the experts. Digi-key has over 13,000 different > power relays over 2 amps, and selecting one, for a novice like me, is a > daunting task. > > The relay is for the e-bus battery feed on a 14 volt system. The load > is currently 12 amps, but I have been challenged to better define my > electrical design objects and possibly reduce the load down to 8 amps. > I don't think that will change the relay selection if I were to use a > design of 5-20 amps. > > I selected TE Connectivity 1432793-1 Automotive relay SPDT 30A 12V. Here > is the link > > > It is non latching with a diode across the coil. Some of the specs, > however, have me confused. > The Coil voltage is 12VDC but the Switching voltage is 14 VDC - Nom. Is > this an issue? > Also the Turn On Voltage (Max) is 7.8 VDC and Turn Off Voltage (Min) 1.2 > Volts. Does this mean that the coil requires 7.8 volts to latch and it > will un-latch if voltage drops below 1.2 volts? > > I see that most of the automotive relays have high ohm resistors across > the coil, or nothing across the coil. When would you select a resistor, > diode or nothing? > > I have another need for a relay in my airplane. My EFIS remote > annunciation mute requires a contact to be close via 2 terminals via a > momentary switch. The vendor does not specify a current requirement for > the switch, and when I contacted them they said any switch would work is > is a fraction of an amp. I would mute the EFIS with one of the buttons > on my control stick, however my control stick only has a common ground, > so all switches close to ground. This would not work for the remote mute. > Is there any reason why a relay wouldn't work? > Would the relay above work? It probably is not the best choice, but it > is only $4 and it would make for common spare parts, so if it would work > it could be my 'best' choice. > > Larry > RV-10 Builder > ========================== ========= ========================== ========= ========================== ========= ========================== ========= > > > > ky=C2=B7=C3=A8=C5=BE=C3=9B"=C3=8D=C3=AD=C5=93=C2=A2Z+=C3=93M4=C3=93G=C3=9A q=C3=A7(=C2=BA=C2=B8=C5=BE=C2=AEw=C2=B0r=B9=C2=AB=B0=C3=C3=93 =C3-=1E=C2=AE=C2=81%y=C3=8Bk=B0=C3=82=C3=A2=C2=B2=C3=91&j)E =C2=A2=C2=BB=C2R=C3=87=C2=AD=C3=A3=1A=C2=B6=C2=BA'=B0=C3=8B =0B=C5-=C3=8BEy=C2=ABn=C2=AD=C3=AB j=C3=B8 j=C3=9A+=C2=B6-=C3=AB=C2 =A3=0B=1E=C2=B6=17=C2j|=B9=C5-=C3=8Bn=C2=B6)b=C2=B6'=C2=AC=C2=B2=C3 =A7!j=C3=82=C3=A2=C2=B2=C3-'=C3=BD+=BA=C2=B1=C3=8A=C3=A2=C2=C3=98 =C2=A8=C5=93 =C3=9C-+=C3=9EI=C3=C2=ABr=10=C3=A8=C3=82yhi=C3=9E=C3 =83k k=C2=A3=0B=1E =16=C2=AD=14=04=0F-=B9h=C2=B2=16=C2=ABy=C2=A9 =C3=9D=C5=A1=C3=A7!=C5=A1=C3=A7!=C5=A1=C5-=C3=9Ej=1A=C3=9E~=1Bm=C2=A7=C3 =C3=B0=C3=83 =C5=A1=C2=B6=C2=BA'=B0=C3=8B=1C=C2=A2o=C3=8Dj=C3=B8 j =C3=9A+=01=C3=C3=A8=12W=C5=93=C2=B6=C2=B8=C5=93.+--=C3=9Bi=C3=C3 =BC0=C3=82f=C2=AD=C2=AE=B0=C3=A2r=C3=87(=BA=C3=B3Z=C2=BE(=1A=C2=B6 =C5-=C3z=C2=BA=04=A2=C3=A7-=C2=AE'=0B=C5-=C3=8B=7Fh=C3=13D=C3 =A3H %=9E=04S=98P=C3=84=99jg =C2=AD=C3=C2=ADr =B0=C3=ADz{Z=93=C3=8A=1A=C2=BD=C2=A8=C2=A5i=C2=B9^=C2=BE&=C2=AD =C3=A5=C5=BElZ+=C2=BAk=1A-=C2=B7=C5=B8-=C3=9Bi=C3=C3=B7=C3 =A8=C2=AE=C3=A9=C2=AC=84=A2=C2=ABk=C2=A2x=C5=93=C2=B1=C3=8A&-=C3=9B i=C3=C3=B7=C3=A8=C2=AE=C3=A9=C2=AC=84=A2=C2=ABk=C2=A2x=C5=93=C2=B1=C3=8A &=C3=BD=C2=A2=C3=A2=C2=B2=C3=90=C2=A8=C5=BE=C3=9A=C3=A2n=C3=ABb=C2=A2u=C5=BE m(=C2=ADy8Z=C5=BEL=C2=A8=C2=B9=C3=BA+=C3=8A=B9=C2=AB=C2=81=C3=A9=C3=9E =C2=AE=B9=C2=AC=C2=B2=C3i=C2=A2=C2=BBLj=C3=9BC=C2=AD=C2=A9ex=C2=B8=C2 =AC=C2=B4=07f=C5-v=C2=A1=C2=AD=C3=A7=C3=A1=C2=B6=C3=9A=7F=C3=0C0=84=A2 =C2=ABk=C2=A2x=C5=93=C2=B1=C3=8A&=C3=BD=C3=8A'=C2=B6=C2=B8=BA=C2=BA=C3 =98=C2=A8=C5=BE=1Bm=C2=A7=C3=C3=B0=C3=83 =C5=A1=C2=B6=C2=BA'=B0 =C3=8B=1C=C2=A2o=C3=9C=C2=A2{k=B0=C2=BB=C2=AD=C5-=B0=C3k=C3 =B6=C3~=B0=C3=AD=C3=BE=C5=A1=C3=9E=C3=BD=C2=BA=1D=C3=8B=C3=B8m=C5=A1 ________________________________ Message 4 _____________________________________ Time: 11:08:28 AM PST US From: C&K Subject: Re: AeroElectric-List: Relays Often when I see two wires like to make some electronic selection I can trace them back and find out that one is actually a ground. Ken On 27/03/2015 1:14 PM, Tim Andres wrote: > And you can pick up that relay or this one: > http://www.bandc.biz/spdtsealedrelay12v40a.aspx > at any NAPA store, they're pretty common. > But there must be a better way to control the EFIS, using a relay for > that function doesn't seem very elegant. What control stick is it? > Tim > > > On Mar 27, 2015, at 9:44 AM, Ralph E. Capen > wrote: > >> I have similar installed in my 6A. That relay will work for both >> applications. Be careful about the relay activation circuit-ground >> the correct side. >> >> >> Sent from my Verizon Wireless 4G LTE smartphone >> >> >> -------- Original message -------- >> From: Larry Rosen >> Date:03/27/2015 09:06 (GMT-07:00) >> To: aeroelectric-list@matronics.com >> >> Subject: AeroElectric-List: Relays >> >> > >> >> I need some help from the experts. Digi-key has over 13,000 different >> power relays over 2 amps, and selecting one, for a novice like me, is a >> daunting task. >> >> The relay is for the e-bus battery feed on a 14 volt system. The load >> is currently 12 amps, but I have been challenged to better define my >> electrical design objects and possibly reduce the load down to 8 amps. >> I don't think that will change the relay selection if I were to use a >> design of 5-20 amps. >> >> I selected TE Connectivity 1432793-1 Automotive relay SPDT 30A 12V. Here >> is the link >> >> >> It is non latching with a diode across the coil. Some of the specs, >> however, have me confused. >> The Coil voltage is 12VDC but the Switching voltage is 14 VDC - Nom. Is >> this an issue? >> Also the Turn On Voltage (Max) is 7.8 VDC and Turn Off Voltage (Min) 1.2 >> Volts. Does this mean that the coil requires 7.8 volts to latch and it >> will un-latch if voltage drops below 1.2 volts? >> >> I see that most of the automotive relays have high ohm resistors across >> the coil, or nothing across the coil. When would you select a resistor, >> diode or nothing? >> >> I have another need for a relay in my airplane. My EFIS remote >> annunciation mute requires a contact to be close via 2 terminals via a >> momentary switch. The vendor does not specify a current requirement for >> the switch, and when I contacted them they said any switch would work is >> is a fraction of an amp. I would mute the EFIS with one of the buttons >> on my control stick, however my control stick only has a common ground, >> so all switches close to ground. This would not work for the remote mute. >> Is there any reason why a relay wouldn't work? >> Would the relay above work? It probably is not the best choice, but it >> is only $4 and it would make for common spare parts, so if it would work >> it could be my 'best' choice. >> >> Larry >> RV-10 Builder >> http://forums.matronics.==========================nbsp; - List >> Contribution >> Wenbsp; &nbf="http://www.matronics.com/contribution">http://www.matronics.com/contrib====================================== >> >> >> >> ky"Z+M4Gq(wr%yk&j)ER' Eyn >> j j+ j|n)b'!j'+ >> +Iryhik k >> hy!!j~m >> 'oj j+W.+-i0fr(Z(z-' hDH %SPjg rz{Zi^&lZ+kikx&ikx&nbum(y8ZL+iLjCex fv-0kx&'m >> 'o{kk~m > * > > > * ________________________________ Message 5 _____________________________________ Time: 02:26:47 PM PST US Subject: Re: AeroElectric-List: Relays From: Eric Page Larry, Ken's comment about tracing the EFIS mute circuit is a good idea, but be careful. There are two ways this circuit could be designed: input pin internally pulled up or internally pulled down. One method (input pulled up) *should* allow you to use your grip switch directly (assuming the EFIS doesn't use an isolated power supply, which is unlikely), but the other method (input pulled down) requires a relay or switch that's isolated from ship's ground. I would contact the EFIS manufacturer again and ask specifically if externally grounding one of the pins will work to activate the mute circuit. If so, problem solved -- wire the appropriate pin directly to your grip switch. If not, and you do need a relay, I can offer this option: I have a few of these relays... http://bit.ly/1Nj9UEt ...that were excess from a past project. I'd be happy to put one on a piece of perforated prototype board with a diode and some Tefzel wire leads (labeled!) and mail it to you. If you want it, just email me your address off the forum and I'll get it out to you ASAP. Cheers, Eric > On Mar 27, 2015, at 8:06 AM, Larry Rosen wrote: > > > I need some help from the experts. Digi-key has over 13,000 different power relays over 2 amps, and selecting one, for a novice like me, is a daunting task. > > The relay is for the e-bus battery feed on a 14 volt system. The load is currently 12 amps, but I have been challenged to better define my electrical design objects and possibly reduce the load down to 8 amps. I don't think that will change the relay selection if I were to use a design of 5-20 amps. > > I selected TE Connectivity 1432793-1 Automotive relay SPDT 30A 12V. Here is the link > > It is non latching with a diode across the coil. Some of the specs, however, have me confused. > The Coil voltage is 12VDC but the Switching voltage is 14 VDC - Nom. Is this an issue? > Also the Turn On Voltage (Max) is 7.8 VDC and Turn Off Voltage (Min) 1.2 Volts. Does this mean that the coil requires 7.8 volts to latch and it will un-latch if voltage drops below 1.2 volts? > > I see that most of the automotive relays have high ohm resistors across the coil, or nothing across the coil. When would you select a resistor, diode or nothing? > > I have another need for a relay in my airplane. My EFIS remote annunciation mute requires a contact to be close via 2 terminals via a momentary switch. The vendor does not specify a current requirement for the switch, and when I contacted them they said any switch would work is is a fraction of an amp. I would mute the EFIS with one of the buttons on my control stick, however my control stick only has a common ground, so all switches close to ground. This would not work for the remote mute. > Is there any reason why a relay wouldn't work? > Would the relay above work? It probably is not the best choice, but it is only $4 and it would make for common spare parts, so if it would work it could be my 'best' choice. > > Larry > RV-10 Builder ________________________________ Message 6 _____________________________________ Time: 03:04:55 PM PST US From: Larry Rosen Subject: Re: AeroElectric-List: Relays > But there must be a better way to control the EFIS, using a relay for > that function doesn't seem very elegant. What control stick is it? > Tim > I confirmed with the company and switching to ground is not what they want. The control sticks are Tosten CS-8 I really like the way the feel and I bought them when I was more electrically naive. My purchase decision may have been different if I knew then what I know now. Thank you aeroelectric. I am not sure how I am going to wire the PTT since the PS Engineering audio panel wants the Mic PTT and Mic Lo switched. Not sure if there is an alternate method or if I need yet another relay. Larry ________________________________ Message 7 _____________________________________ Time: 08:14:58 PM PST US From: Bob McCallum Subject: RE: AeroElectric-List: Relays Larry; Although you have received some anecdotal responses to your relay question I'll try to directly answer each of your specific questions. 1: The 30 amp relay you have chosen will safely switch loads from a fraction of an amp up to its 30 Amp rating, so you are correct in the assumption that, within reason, your endurance buss load is immaterial to relay choice. 2: A 12V automotive relay is designed to function in the automotive/vehicular world, therefore any voltage from 9-10 up to 15-16 will be happily accommodated. Your 14V is not an issue, this is "standard" vehicular voltage. If you look at the spec sheet for the relay you've chosen the contacts are rated for 16 volts by the manufacturer. 3: Turn on voltage (max) 7.8 means that if you were to slowly increase the voltage across the coil from zero that by the time it reached 7.8 the contacts would have transferred to the on condition. (not latched as you have stated, this is NOT a latching relay) They might transfer at some value below 7.8, but will have transferred for sure by 7.8. 4: Turn off voltage (min) 1.2 means that if you were to slowly decrease the voltage across the coil from the rated 12 volts down to zero, the contacts would have transferred to the off state by the time the voltage reached 1.2 volts. They might switch off at some level above 1.2 but for sure they will be off by the time you reach 1.2. (your interpretation of turn on/turn off voltages is correct, but again this relay does not unlatch by 1.2 volts as it is not a latching relay. The contacts simply transfer back to the "at rest" position) 5: I don't see where you found relays with resistors across the coils. They do exist, but the coil resistance numbers in the Digikey relay tables refer to the resistance of the coil itself. It is only meaningful with respect to the amount of current drawn by the coil when energized and if you are using a 12 volt relay in a 12 volt system it's not something you generally need worry about. Components added across relay coils such as resistors and diodes are introduced in an effort to reduce the inductive effects of turning off the coil. The action of turning off an inductive load (the relay coil) imposes momentary high voltages (inductive spikes) across the switch contacts which control the coil causing arcing and possibly reducing the life of the switch contacts. A resistor provides an alternative path for the inductive current to dissipate and a diode effectively "shorts" the inductive current. There are many arguments for each of the methods of reducing this effect with some advocating diodes as being the most cost effective solution while others maintain that the slightly increased switching time caused by the diode is detrimental. Others advocate MOVs, resistors, or bi-directional zeners, while some suggest nothing is required. The simple diode installed by some manufacturers, such as the one you've chosen, seems to be the most widely accepted cost effective method of mitigating this effect. 6: This relay would "probably" work for your EFIS issue BUT you might possibly need gold contacts for that application if the current being switched is low enough. For extremely low currents there is insufficient arcing to keep silver/tin oxide contacts clean and the oxidation which forms on them will insulate against very low currents, hence the need for gold contacts in signal level circuits. ( and no you can't use the gold contacts for high currents as the arcing will destroy the ultra thin gold plating.) Hope this somewhat solidifies your understanding of the terminology you've questioned. Bob McC > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list- > server@matronics.com] On Behalf Of Larry Rosen > Sent: Friday, March 27, 2015 11:07 AM > To: aeroelectric-list@matronics.com > Subject: AeroElectric-List: Relays > > > I need some help from the experts. Digi-key has over 13,000 different > power relays over 2 amps, and selecting one, for a novice like me, is a > daunting task. > > The relay is for the e-bus battery feed on a 14 volt system. The load > is currently 12 amps, but I have been challenged to better define my > electrical design objects and possibly reduce the load down to 8 amps. > I don't think that will change the relay selection if I were to use a > design of 5-20 amps. > > I selected TE Connectivity 1432793-1 Automotive relay SPDT 30A 12V. Here > is the link > > > It is non latching with a diode across the coil. Some of the specs, > however, have me confused. > The Coil voltage is 12VDC but the Switching voltage is 14 VDC - Nom. Is > this an issue? > Also the Turn On Voltage (Max) is 7.8 VDC and Turn Off Voltage (Min) 1.2 > Volts. Does this mean that the coil requires 7.8 volts to latch and it > will un-latch if voltage drops below 1.2 volts? > > I see that most of the automotive relays have high ohm resistors across > the coil, or nothing across the coil. When would you select a resistor, > diode or nothing? > > I have another need for a relay in my airplane. My EFIS remote > annunciation mute requires a contact to be close via 2 terminals via a > momentary switch. The vendor does not specify a current requirement for > the switch, and when I contacted them they said any switch would work is > is a fraction of an amp. I would mute the EFIS with one of the buttons > on my control stick, however my control stick only has a common ground, > so all switches close to ground. This would not work for the remote mute. > Is there any reason why a relay wouldn't work? > Would the relay above work? It probably is not the best choice, but it > is only $4 and it would make for common spare parts, so if it would work > it could be my 'best' choice. > > Larry > RV-10 Builder > > _- > ===================================================== > ===== > _- > ===================================================== > ===== > _- > ===================================================== > ===== > _- > ===================================================== > ===== > > ________________________________ Message 8 _____________________________________ Time: 09:31:24 PM PST US From: Larry Rosen Subject: Re: AeroElectric-List: Relays Bob McC, Thanks, very helpful. It did help solidify my understanding. Would you help me identify a relay that would be a better choice, or point me into the right direction. It doesen't look like the automotive type relays have gold contacts they are designed for high (10A and above) loads. Larry On 3/27/2015 11:13 PM, Bob McCallum wrote: > > 6: This relay would "probably" work for your EFIS issue BUT you might > possibly need gold contacts for that application if the current being > switched is low enough. For extremely low currents there is insufficient > arcing to keep silver/tin oxide contacts clean and the oxidation which forms > on them will insulate against very low currents, hence the need for gold > contacts in signal level circuits. ( and no you can't use the gold contacts > for high currents as the arcing will destroy the ultra thin gold plating.) > > Hope this somewhat solidifies your understanding of the terminology you've > questioned. > > Bob McC > > >> -----Original Message----- >> From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list- >> server@matronics.com] On Behalf Of Larry Rosen >> Sent: Friday, March 27, 2015 11:07 AM >> To: aeroelectric-list@matronics.com >> Subject: AeroElectric-List: Relays >> >> >> I need some help from the experts. Digi-key has over 13,000 different >> power relays over 2 amps, and selecting one, for a novice like me, is a >> daunting task. >> >> The relay is for the e-bus battery feed on a 14 volt system. The load >> is currently 12 amps, but I have been challenged to better define my >> electrical design objects and possibly reduce the load down to 8 amps. >> I don't think that will change the relay selection if I were to use a >> design of 5-20 amps. >> >> I selected TE Connectivity 1432793-1 Automotive relay SPDT 30A 12V. Here >> is the link >> >> >> It is non latching with a diode across the coil. Some of the specs, >> however, have me confused. >> The Coil voltage is 12VDC but the Switching voltage is 14 VDC - Nom. Is >> this an issue? >> Also the Turn On Voltage (Max) is 7.8 VDC and Turn Off Voltage (Min) 1.2 >> Volts. Does this mean that the coil requires 7.8 volts to latch and it >> will un-latch if voltage drops below 1.2 volts? >> >> I see that most of the automotive relays have high ohm resistors across >> the coil, or nothing across the coil. When would you select a resistor, >> diode or nothing? >> >> I have another need for a relay in my airplane. My EFIS remote >> annunciation mute requires a contact to be close via 2 terminals via a >> momentary switch. The vendor does not specify a current requirement for >> the switch, and when I contacted them they said any switch would work is >> is a fraction of an amp. I would mute the EFIS with one of the buttons >> on my control stick, however my control stick only has a common ground, >> so all switches close to ground. This would not work for the remote mute. >> Is there any reason why a relay wouldn't work? >> Would the relay above work? It probably is not the best choice, but it >> is only $4 and it would make for common spare parts, so if it would work >> it could be my 'best' choice. >> >> Larry >> RV-10 Builder >> >> _- >> ===================================================== >> ===== >> _- >> ===================================================== >> ===== >> _- >> ===================================================== >> ===== >> _- >> ===================================================== >> ===== >> >> > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.