power seats controls w transistors

Hi. I am new to this forum and not English speaking so my spelling may be a little off. I have some questions about controlling motors in power seats. I have two comfort seats from a BMW e60 and they are originally controlled by can bus and the modules is fitted under the seats. I have semi elictric seats in my e60 and if I change to the new seats I have to go to my dealer and reprogram the car to get the power seats to work. And rewire the can bus too. But I wonder if there is other ways to do this. If I sell the car I want to keep the seats for my old car so I need to rebuild the controls. So what I want to do is use small joystick controls to control relays that change polarity to the actuators and also to control the valves in the lumbar support. The joystick control cannot handle the current to operate the relays so I have to use transistors I guess. I need help to dimension this transistors, resistors and, if there need to be diodes on the relays, the type of diodes. I think the joystick can handle about 20mA. I will use small relays fitted on a card. The old seats have a switch that controls the two motors directly, so it should work to tap power from that cables. I have drawn a layout and would appreciate opinions about if it can be done. Thank you in advance as we say in Sweden.No reason not to try

Damn Swedes - you are worse than Turnips! Since you are using then a switchers (on-off) and not analog, I reckon power FETS (MOSFETs) are much easier. These can handle several Amps and are voltage switched (rather than transistors which need current and have a gain - ie, 20mA joystick to 5A = 5/0.02 => gain > 250 which is 2 transistors - say gains of 30 & 10 = 300; though <20mA to a >250mA relay coil is easy enough).     And MOSFETs that handle 60A can be as cheap as a few dollars. How's that sound - one MOSFET to switch the motor direct from the joystick? Although since polarity reversal is required, maybe a DPDT relay instead.. or as well.... But please confirm: - the joystick is a switch type (not analog resistive); - you don't mind +12V or GND switching (of the joystick)?     [ LOL! As I write this I am watching the TV music show "Spicks & Specks" on my PC. They mention Sweden's music exports - like Blue Swede, Abba, .... Meanwhile I think of Mikael Rickfors, Revanche (Kjänn Draget), Driller Killer, not to mention Refused! ]

Hi! Great you know some about Swedes! We had a culture-collision when my girlfriends relatives from Perth visited us som years ago. We found out we really didnt know anything about Australia and they knew very little about Sweden. We are not only ABBA and Bjorn Borg and you are not only Steve Irwin. (when he was alive anyway). Back to topic: The joystick is a switch. It sounds good with MOSFETs to operate. And there is no problem to use 12v on the joystick. But since I dont understand the electronics here I have to ask: could 12v cause problems? I think the important fact is the current through the contact in the joystick? How do I dimension this? I will use 2 alternating 1 pole relays to each motor, in all 9/seat. So this is why I need small joysticks: it will be a lot of big buttons. It looks like i need 4 MOSFETS or 2 transistors and 2 relays. Could you help me a little further? ThanksNo reason not to try

Oh geez I know about that culture collision! There is a federal election looming and those Waussies & Perthians think they are funding the whole country. This might be their go for independence. Forget the centuries of subsidising their economy and under 1 person per square kilometer. I reckon leave them to themselves; change the old Brisbane line to the WA line, and let our northern neighbours have them. We'll pull out Defenses east of WA, severe the WA OTR radar links, and finally be rid of WA beer. That'll take "Boat People" off our election issues. (For those that don't know, Refugees & Asylum seekers are "illegal immigrants" and everyone (especialy Aussies) know that Orstralia is the destination of choice. Yep, these Ozzies are a clever bunch. Banana Republic isn't it?) We'll still charge interest on Alan Bond's debt, and take credit for winning the America's Cup.    The 12V shouldn't cause joystick problems - it's more a case of limiting current. And 1mA is enough to drive one transistor to drive a relay; 1uA or 1nA is enough for a FET to do the same. The circuit would be similar to what you have drawn except the switch (joystick) would be fed from +12V into a resistor to the FET (with another resistor to GND to ensure the FET turns off), and the FET connecting from GND to the relay. Or similar. I'll check around to see what I think should suit. Or maybe the other gurus on here have something. BTW - it was Jens Lekman that was on that TV thingy. I have no idea who he is - at first I thought it was Dennis Lyxzén. Political bullsh written and unauthorised by OldFart on behalf of other Aus expats.

The fun in this is you are telling me things I should know. I´ve been an electrician for 15 years for gods sake! And now constructing in Inventor 3d CAD. The problem is since I have not used my knowlegde since school it´s gone. Electronics is suprisingly far from working as an constuction electrician. I´m back to school again anyway, in my spare time, and this can come in handy, the next course is automation. I opened the original module in the seat, the module I like to replace. There are relays on the outputs there too, but it seems like only one for each actuator. They have 8 pins. I will investigate this. Maybe I can use them if they are some kind of double relay with 2 coils? But the 6 pins can be a double alternating rocker too with one coil. Then the polarisation changing must happen before the relay? This is strangely interesting. From a practical issue it has moved to being a project to learn from. Maybe I will put the seats in my 1600 touring instead just for fun. Even I dont know what Jens Lekman looks like so I will check that too. Political bullsh is a source of laughs to me. Sometimes politicians trip over humor and get suprised themselves. No reason not to try

Yes but I watch Wallander and Oldspark should I tell your friend where your family comes from?

Howard PLEASE! This is a family site - keep it clean. I'm sure the Swedes of all people know where people come from. However Swede's not knowing much about Australia - that is a change - that takes me back to when Australia was a small European country near the Alps (they bred dictators) and Sweden was a small neutral European country in the Alps (they were still bordering each other on the last map I saw). Maybe the 40,000 Swedes (per annum?) that toured here (aka Cairns) are long gone? As long as kullakra isn't like a certain other "experienced" Swede that blames everyone else for being wrong... (And despite his years of experience does some very strange things - I suspect he has more time & money than sense - the negative impacts of a high standard of living LOL!) Now if there was only one-L in kullakra I'd feel safe.... As to Wallander, I think most hereon would agree the original series is best. (Why remake it in English? Isn't that for the yanks?) kullakra - if relays are ok, the basic connection is simple.... EG - see 12volt's Relay Diagrams - Door Locks - Actuators / Reverse Polarity - Positive Switch/Trigger... ie: That may be better understood from posts like reverse voltage for boat, especially page 2. And hotwaterwizard had a few here and there - eg, solid-state (no relays) at reverse 12v motor relays where transistors could be replaced by FETs... But why not start with two SPDT relays per motor and see how that goes.    The main joystick issue is limiting current to under 20mA which means at least ~700R (R=Ohms) relay-coil resistance. In practice that means a transistor or FET per contact/relay (and 1 or 2 resistors) and various examples in here (the12volt) can be used. But is it worth trying the relay connectivity first? 2 SPDT relays that handle the 5A motor current. Why not common 12V 15A or 30A SPDT relays (5 pins - they have both 87 & 87a terminals). And actuate the relays one at a time - though the motor is supposed to be stopped before reversing direction. (Having both relays off or both on is not a problem.)

Well I guess you´re not from Australia then, but I don´t need to know that. And Howie: Dont tell if its some kind of secret. I am glad to get help with the seat controls-thats all. No need to make fun of me. And I really dont have more time and money then sense. I missed the fun in Kullakra with one L though? The relay connections is no problem. This I know. The question is about operating the relays with less current through the joystick. and I have to use small relays to fit under the seat. Not much room there. There will have to be 18 relays to operate 9 motors? With the lumbar support 2 more. Operating the relays together is no problem I think. The joystick can only close one contact at a time. And the gearbox will stop the motor at once when the button is off. And the motors are with built-in limiters (bimetal?) So I would appreciate a layout with values and placing of the components regarding resistors, transistors(or MOSFETs) and eventually diodes to make this work. Or point me to another example that may work in the forum. The hotwaterwizard connection nr2 is what I will use but this have to be contolled by the joystick. Your help is appreciated. Thank you No reason not to try

Just found out about the relays: G8NW-2, it is 2-coil relays for automotive use. So I will use them.No reason not to try

https://www.the12volt.com/installbay/forum_posts.asp?tid=114792&KW=2n6491#556471

The current draw from your switch will be minimal, the diagram says from your 500 MA output.  That is for his application.  The draw on your switch will be well below your 20MA.