nice pdf relay reference

http://www.dlcparts.com/images/BoschGuide.pdf

Came across this nice guide to relays with a bunch of useful configurations-  might be useful to you guys-

Good find. Funny how it's over 15 years old and yet looks so familiar... But beware, it does have some convention errors (like +ve to 85 & GND to 86) and some other strange things (like a relay for a flashing LED when IGN is off? C'mon! And no points- or ignitor-shorting ignition kill but power-interrupting ign kills?).

I thought the circuit to make your car horn honk when you get a call on your cell phone might have dated it some.  I guess that was for those permanently installed car phones.

The cigarette lighter kill switch one was a interesting one in that it provided for a normal functioning lighter socket after starting-

oldspark wrote: strange things (like a relay for a flashing LED when IGN is off?

I thought that strange too, but figured it was supposed to be for some kind of phony alarm indicator to fake out would be thieves, for those who didn't want to bother installing an actual alarm.

dualsport wrote: The cigarette lighter kill switch one was a interesting one in that it provided for a normal functioning lighter socket after starting-

Idea was there, but looking at the diagram, for some reason it was drawn with a bypass over the key side starter signal, which should actually have been connected to provide the power for the relay coils.  The way it was drawn, there's nothing to power up the relays.

dualsport wrote: I thought that strange too, but figured it was supposed to be for some kind of phony alarm indicator to fake out would be thieves, for those who didn't want to bother installing an actual alarm.

No, my point was why add a relay when the flashing LED can simply be places across the IGN & constant lines - ie, Led+ to +12V and its -ve to IGN +12V? It would be even sillier if the 50mA to 200mA relay coil was energised whilst the 20mA peak but probably 1mA - 5mA average flashing LED was flashing.   (Instead the relay can only be on when IGN is on and its ~200mA drain should hence be insignificant.) Yet I see many such circuits whether it be transistorised circuits added for a motorcycle indicator buzzer, or even ICs for simple high/low level pump switching when the mere 2 switches and a plain SPST relay can do that (ie, see my 2-switch & single relay latching relay circuit; that was originally devised as a water-tank level maintainer or bilge/sump drainer). [ I don't think my latching relay even appears in that document!! ] If extra processing is required like delays or timers etc, then fine. But the instances I speak of do not incorporate that. Granted, maybe I have some uncommon ability to simplify circuitry by using phantom or wired-OR (aka switched) grounds and other novel techniques, but to see such added and unnecessary circuitry survive in such publications or even appear in certain regular magazines etc leaves me somewhat puzzled, else feeling smugly superior LOL! As to the logic of that cig socket stereo circuit... You lose the function of the cig socket, hence no plug-in chargers or lighters etc. How to you activate the stereo if you misplace the cig plug? Why not leave the OEM cig socket wire uncut and instead install a separate switch? But why would you want that anyhow? FWIW... I recently had an issue with my traditional connection of BOTH HU ACC +12V or IGN and constant +12V direct to the battery. Unlike my older Alpines (and 2 other interim pieces of junk), my new Alpine has a drain of ~110mA when both +12V sources are connected to +12V, hence flattening my battery. The problem was solved with someone's brilliant latching relay circuit (guess whose?)... The dedicated fused battery +12V went as normal to the Alpine constant. But that +12V also went through a relay to the Alpine's switched +12V input (in #30, out #87). The relay coil's #85 went as normal to GND whereas the coil's #86 was powered both from the Alpine's "remote" output and via a blocking/isolating diode from IGN +12V. (I probably included a diode from the remote output.) Hence normally you can't turn on the HU.   But with IGN on, the relay energises so the HU's switched +12V is powered hence I can turn the HU on. (The Alpine will power itself on if its last power-off was not through its power switch, ie, if power-off was due to a loss of its switched +12V supply.) Once on, the HU keeps itself on irrespective of IGN or ACC because its remote out keeps the relay energised. Hence my old normal situation where I had to power it off via its own power switch. (And don't worry, that's a decades-old habit for me. My only problems were the rare cases I forgot I merely paused my Alpine that had a blown faceplate, and I couldn't see that it was on when I left the car.) I did intend to add extra switching so I could turn on the HU without an IGN key (eg, bridge #30 to #87 via a push-button and diode), and have the IGN/ACC turn off the HU automatically (ie, break the remote to #86 connection). Maybe one day I'll bother adding that, but IMO it's such a trivial enhancement for now.    Geez, maybe I should Patent or Copyright that circuit too?

Yeah, relay is not necessary with the low draw of an LED making the use of a virtual ground switch via ignition switch feasible. Case of a relay solution looking for a problem -  To sell more relays maybe-

The cigarette lighter disable was supposed to be for a starter kill, not stereo- idea just to add something to help thwart the joyriders, since it's not a common procedure to expect to have to plug in a lighter to start a car..  Again maybe dated with the more sophisticated theft prevention devices nowadays, but could be useful.  The relay in the diagram enables the lighter socket to remain functional, so it's not as bad.

 There's often better ways to do things, but sometimes they get passed over because they're not understood as easily or more involved.  Even here there's still the diagram using a huge cap for relay delay timing instead of a transistor drive circuit, because some shun solid state stuff.

But, as long as the ideas get planted to get people to think about the different ways possible, it's all good. 

Was that "someone else" someone I know? Yes latching relays with dual coils are so obvious and useful to someone like me who can't get his head around trannies. Yes I found that Bosch guide rather twee but dated bit like an old school book from the 1960s. Also the same praise to dualsport for digging it out it's still a good reference.

I can't agree more about the planting of ideas. Even I still get new ideas and entire brainstorms and philosophies from looking at such collections. Even the misapplied or wrong solutions can trigger events. One of my most significant recent examples of such is a fuel-pump relay circuit that a clever dude posted on a car forum that I was once involved with. Even though I had a brilliant and clear car circuit diagram (that was posted by another member) that showed the relevant circuit (it even showed the relay and alternator contacts involved - ie, similar to how I draw my posted circuits!), and I understood what was involved, it wasn't until I saw the simplified diagram, namely: ... that the method's simplicity and brilliance hit me. Of course the aforementioned member's cleverness is obvious by his use of a the12volt.com relay diagram - not that I need to push that score ha ha! However it was that the12volt-based diagram that led me to eventually realising how totally flawed the common practice of using an oil-pressure switch to control fuel pumps was - especially in carbureted vehicles! [ Admittedly that took a further 6 months and was only because I persisted in trying to simply combine the two methods without the need for a +12V 2-wire oil-pressure switch - until the obvious and simple solution(s) hit me! ] And that was despite me "fully understanding" the circuit itself and seeing how it also controlled an optional fuel-cut valve (presumably on engine-pumped vehicles) as well as the electric choke. Later came the UIBI or "Ultimate Intelligence Battery Isolator" which is simply a DIY charge-light energised relay - ie, the same as the above fuel pump circuit. I clicked to that when pondering the repair of my voltage-controlled battery isolator after it got washed. Somehow I thought of that circuit and the rest is history. And though others implemented the same UIBI-type isolator way before I did, I have since managed to save many people lots of money, and provide a superior solution to boot. Then come the enhancements that can be added by the simple addition of switches or timers etc and maybe isolating diodes - eg, manual connection for jump-starting, delayed connections, low-voltage cut-outs, etc. They are most often merely a switch & diode or other simple circuits - eg, my latching relay, or an MW728 "battery protector" with novel wiring. [ Note - with a diode in the STARTing and REG inputs to that fuel-pump relay and instead connecting them to the relay's coil #86 with a fused battery +12V to #87 means an SPST relay can be used to provide both the priming and "running engine" fuel pump functions. But the SPDT relay is a straight addition without the need for diodes, however that particular vehicle has two ignition-switch Start/crank terminals in case that matters. (The dioded SPST version has no such dependency nor complication.] And if adding a momentary and switched manual bypass to manually energise & hence join the batteries, those diodes may as well be used so the coil #86 has a collection of diodes each connecting its own particular trigger or controller. ] Granted, that ramble was about exponential developments from a simple and correct relay circuit. But similar has occurred thru other "stupid" or wrong ideas and circuits. Actually the only problem I have had with such developments is in dealing with others. Though my & similar ideas have given me and others easy, cheap, reliable and superior DIY solutions, there are those that don't click nor accept them. In fact I'm dealing elsewhere with such an issue at the moment, but once I get the person involved to finally see that I am talking about batteries that are paralleled only whilst charging... (Ironically we both agree on the need to match parallel batteries etc, but whereas I maintain matching is not required when isolators are used, he keeps returning to his teachings and problem experiences, but they are all when NOT charging and left paralleled. But he should soon click.) Not that that's a problem other than the excessive time spent - that's just part of the deal - but I think of other "experts" that are simply so moronic. A particular thread involving oil-pressure controlling their fuel pump comes to mind. [ Honestly, a true bunch of fools. Some openly contradict their own statements and others pop in with stupid scenarios that show they have no understanding whatsoever. I did warn them - albeit subtly - and I await the day they finally click, and furthermore realise how ridiculous and embarrassing their replies were. This is from a group of well respected bunch of sophisticated CPU/ECU hackers. One even wrote how he AND his electrician dad could not get "my"(sic) fuel pump circuit working, yet many others on a related plain ordinary car forum have! Oh well... At least that still-existing and public thread has given many in the know a good belly laugh or ten! ] Hmm - has anyone heard of "the wrath of an OldFart"? Oh dear, I've hijacked this thread... Or am I lucky it's dualsport's thread and acceptable? (IE, the OP is a "solved issue" and hence offshoots are not such a crime?) And truly, I did just want to emphasis how IMO important and welcome links or documents as in dualsport's OP are... 10x

Damn, I missed Howard's reply. (Hey, did I say welcome back?) Nah man, I'm talking my stock standard SPST relay that latches. It is merely a single connection. Add a push-to-energise switch if desired.    Add a push-to-switch-off switch if desired. And, if the load is bigger than the switches can tolerate, add at least one diode, or one diode per switch. Generally I far prefer that to the equivalent 3 & 4 relay versions I have seen. I was considering using the above SPST circuit to replace my faulty voltage sensing battery isolator's defunct latching relay, but that's a true latching 80A relay that doesn't draw power except when switching. And since that circuit only draws 4uA or a bit more with an indicator LED (~50uA?) and I also use it as a battery low-voltage isolator (the same thing as a typical voltage controlled battery isolator but with lower voltage settings) on solar & total-waste battery systems, I'm keen to use its original 80A latching relay. Besides, the relay only costs $5 and the complete kit (without housing) costs a mere $22. [And that would be my voltage controlled or "smart isolator" suggestion for anyone needing or wanting those. And preferable to the similar priced 10mA-drawing MW728 10A battery protector provided its size and construction and extra housing wasn't an issue.] I was also going to say how those delay-relay "solid-state shunners" also have to contend with high in-rush complications (as per 2 recent the12volt threads) and occasional relay chatter problems. But I seemed to have forgotten to include that...