stereo wiring

[maloneduke]

so im going to install my stereo in my 69 bug. i was told i should install an on/off switch on the power wire so i can run the stereo without burning up my coil. my question is do i run the now switched power wire to an always hot fuse or do i stick with a switched fuse?

[Cusser]

If you keep the stereo's power wire (typically red with an in-line fuse), any switched fuse location will still energize the coil.

If you want the radio to be used separately, you need to wire up to a fuse box location like used for the dome light. That's where the stereo's yellow memory wire will be attached (clock and station memory).

For the record, my 1970 VW was wired with constant power to its radio from the dealership, I had to remember to switch that off, not a big deal. My 1971 VW had its radio on switched power. I bought these each in the 1970s with 2 and 5 years on them, o that' the way their dealers installed them.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[ashman40]

Can you detail what it is you want to do with your stereo? What is it you are expecting?

I'm guessing you want to park the car, turn off the engine (to protect the ignition) but continue to listed to the stereo?

There are a few ways I can imagine doing this...

(Simplest) Connect your stereo power wire (red) to a constant 12v source at the fuse box. On a 10-fuse '69 fuse box this would be fuse #9 or #10.
Down side, if you forget to turn off the power switch for your stereo when you leave the car you will return to find a dead battery.

(Simple switch) Add a toggle switch to select whether your stereo is powered from the ignition switched circuit or from a constant 12v circuit. Normally, it would be left on the ignition switched circuit, but when desired you would flip the SPDT switch and change the power source to the constant 12v so you can listen while the engine/ignition switch is OFF.
The downside of this is the power to the stereo will be momentarily disrupted when you flip the switch causing the stereo to reset and for a few seconds your music will be disrupted.
Again, it is possible to forget to reset the switch to the ignition switched side and your stereo is ON even after you walk away from the car. You return to find a dead battery.

(More complicated/expensive) Add a dedicated 12v battery just for powering your stereo. A small lead acid battery for a home security system is enough to power your stereo. Add a battery isolator as used in RV homes will allow the battery to be charged while the engine is running but disconnected when the charging system is OFF. From that point the stereo runs from the spare battery only. If you forget it does not drain your main battery, just the small one. If the small battery is a deep-discharge it can be recharged fully with little issue.
Because the stereo is actually always running from the smaller spare battery power is not disrupted when the ignition is turned OFF. You can still drain the spare battery but will not be left stranded if you forget to turn off your radio.

(Much more complicated) Add a bypass circuit made from a couple relays and a capacitor powered circuit. Tied into the ignition circuit, the constant 12v power source and the door switches... the circuit provides power to the stereo when the ignition is turned ON. The relay is energized and actually powers the stereo from a constant 12v source. The capacitor circuit momentarily powers the power relay as the ignition switch turns OFF so power is not disrupted. The whole system remains powered until the door switches indicate a door has been open. At this point the entire circuit is powered OFF and reset to be powered up the next time the ignition switch is turned ON.
I built this circuit for my '75 Beetle so I could turn off the engine and continue to listen to the stereo even if I removed the key from the ignition. But as soon as I opened the door the stereo would turn OFF so I could never forget to turn it OFF (unless I fell asleep in the car listening to the stereo ).

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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[maloneduke]

yeah park and listen...
so im thinking the simplest one you explained. the reason i want to run a switch is because when i hook both power wires to hot fuses the stereo wont turn off at all. so im thinking that by running a switch through the power wire to a hot fuse will insure that it gets turned off, and the switch im using is lighted so im hoping that will somewhat make it idiot proof, but who knows....

[ashman40]

You should look for a SPDT switch. These have a single common terminal and two outer terminals that connect to the common terminal depending which position the switch is in. Most of these are 2-position switches (ON1 - ON2), but there are 3-position versions with an OFF in the center position which completely disconnects the common (ON1 - OFF - ON2). This would give you control to shutoff the radio even when the ignition is ON.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[johneliot]

A switch to turn off the stereo as opposed to turning off the stereo? Things that make you go hmmmmmm.
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John

There is no distinctly American criminal class - except Congress.
Mark Twain

69 bug - "The Grey Ghost"

[HarrysRatBug]

Could put a hidden switch that would turn off power to the coil. When you want to listen to the radio with the car off just leave key on and kill the power to coil. When done listening turn key off. No dead battery. Just have to remember to turn coil switch back on when wanting to start. Kind of theft prevention too, just not much!

[jetmech]

one thing I did for my daughters 74 super is that I wired the ignition coil from the key to a switch then to the ignition coil. it serves 2 purposes 1; it acts like an anti theft switch cause you can't start the car without the switch on and 2; if you want to park and listen to the radio or go to the drive in (yes they still do exist) then you can have the key in the ACC position and turn the coil switch off so you do not burn out your coil.
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74' Super Beetle

[Jimbug57]

I used always on/fused LED toggle switch for my satellite radio.

I really like the idea of a spare battery/isolator. I'll put a 12v accessory jack in the circuit, too.

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Repeat after me "I am smarter than metal!"

[Gerrelt]

If you want to use a normal switch (instead of a SPDT one), you have to use a diode. Otherwise you will feed the power back to the fusebox, which will be like putting the ignition on.

I've made a video on this subject, it includes instructions on how to wire it:


Link


The SPDT switch option is a lot simpler to instal, but a switch like that is a bit harder to find.
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[mondshine]

Here's how I wired the radio in my '71 Super many years ago.
This setup takes advantage if the stock door buzzer circuit.

The radio will operate with the key in the ignition switch, and turn off when the key is removed.

Caution:
Most modern radios now require constant power to the yellow wire, and switched power to the red wire, so check your radio's instructions.

Good luck, Mondshine

[hulbyw]

"(Much more complicated) Add a bypass circuit made from a couple relays and a capacitor powered circuit. Tied into the ignition circuit, the constant 12v power source and the door switches... the circuit provides power to the stereo when the ignition is turned ON. The relay is energized and actually powers the stereo from a constant 12v source. The capacitor circuit momentarily powers the power relay as the ignition switch turns OFF so power is not disrupted. The whole system remains powered until the door switches indicate a door has been open. At this point the entire circuit is powered OFF and reset to be powered up the next time the ignition switch is turned ON.
I built this circuit for my '75 Beetle so I could turn off the engine and continue to listen to the stereo even if I removed the key from the ignition. But as soon as I opened the door the stereo would turn OFF so I could never forget to turn it OFF (unless I fell asleep in the car listening to the stereo Razz )."

Ashman40, this is just what I would like. Any chance you could post up a circuit diagram? I'm no electronic expert but I am capable of assembling simple circuits and making my own circuit boards and comfortable working with relays
Cheers