[scanboy]

Hi, I'm trying to install a license plate review camera. The camera works, the problem is my monitor. The monitor I have is the Alpine TME-770 (pretty old but works perfectly), and it will switch to video input 2 when I put into reverse, under the condition that I provide a 12v (reverse light +) to one of the wires. Anyway, I did that and it all works when power is on (engine off), but as soon as I turn on the engine, the reverse light + drops to 10v, that cause my monitor NOT to auto switch to video input 2 (camera).
So my question is, is there any way I can maintain that 12v my monitor needs after engine starts? is there something I can buy to make 12v from a 10v source? Help!!!

[Technic]

Originally Posted by scanboy

Hi, I'm trying to install a license plate review camera. The camera works, the problem is my monitor. The monitor I have is the Alpine TME-770 (pretty old but works perfectly), and it will switch to video input 2 when I put into reverse, under the condition that I provide a 12v (reverse light +) to one of the wires. Anyway, I did that and it all works when power is on (engine off), but as soon as I turn on the engine, the reverse light + drops to 10v, that cause my monitor NOT to auto switch to video input 2 (camera).
So my question is, is there any way I can maintain that 12v my monitor needs after engine starts? is there something I can buy to make 12v from a 10v source? Help!!!

A relay will work... replace the "remote turn on lead" wire shown below with your 10v source and connect the "Additional Accessories" wire below to your TME-770 reverse wire:

[scanboy]

Originally Posted by Technic

A relay will work... replace the "remote turn on lead" wire shown below with your 10v source and connect the "Additional Accessories" wire below to your TME-770 reverse wire:

Really? a relay would work? Please excuse my ignorance in electronics, but I thought a relay is like a mechanical switch, if the power I provide to the red lead is 10v, wouldn't I get 10v also in the additional accessories? Or I really need a 12v to the red in order for this to work? I'm not sure if I can provide that 12v, I only did a measure to the reverse light + after engine start and it is 10v, so I was assuming that all other "12v" (cigarette etc) will give me 10v also after engine starts. I'll do some measuring to see if I can get 12v somewhere else, if so, this might be my solution.

[Technic]

Originally Posted by scanboy

Really? a relay would work? Please excuse my ignorance in electronics, but I thought a relay is like a mechanical switch, if the power I provide to the red lead is 10v, wouldn't I get 10v also in the additional accessories? Or I really need a 12v to the red in order for this to work? I'm not sure if I can provide that 12v, I only did a measure to the reverse light + after engine start and it is 10v, so I was assuming that all other "12v" (cigarette etc) will give me 10v also after engine starts. I'll do some measuring to see if I can get 12v somewhere else, if so, this might be my solution.

The whole idea of using a relay in your application is to "convert" 10V into 12V, as long as you use 12V in pin 87 as shown in the diagram above.

[jzchen]

A possible reason it might be at 10V is that you are drawing too much current with your tap that the circuit can't keep it at 12V. I have to agree that a relay is your best bet.

[VP Electricity]

The problem is that you don't know the current capability of the "10V" wire... you would be better served with a low-voltage trigger device that doesn't require the factory wire to energize a relay coil. I think the PAC # for that is TR7, and I have used the Directed RTO widget for that too.

[scanboy]

Originally Posted by jzchen

A possible reason it might be at 10V is that you are drawing too much current with your tap that the circuit can't keep it at 12V. I have to agree that a relay is your best bet.

Possible, I only know that the camera draws about 100ma, but don't know about the monitor. I did a measure at the power source of the monitor (cigarette lighter), it is still at 12v, and if I use this as trigger to the auto switching, it seems to work fine, so some method (relay etc.) to get trigger from reverse bulb +, and use the same power source of the monitor to do the actual power feed.

Originally Posted by VP Electricity

The problem is that you don't know the current capability of the "10V" wire... you would be better served with a low-voltage trigger device that doesn't require the factory wire to energize a relay coil. I think the PAC # for that is TR7, and I have used the Directed RTO widget for that too.

You mean TR7 instead of relay or TR7 as trigger to the relay? Sorry, never used TR7 and don't even know what it is.

[jzchen]

Here's a TR-7 that I found. I think a relay is cheap enough to be worth a shot before trying this though...

http://www.rainbowappliance.com/TR7....PID=9638995910

[jzchen]

Originally Posted by scanboy

Really? a relay would work? Please excuse my ignorance in electronics, but I thought a relay is like a mechanical switch, if the power I provide to the red lead is 10v, wouldn't I get 10v also in the additional accessories? Or I really need a 12v to the red in order for this to work? I'm not sure if I can provide that 12v, I only did a measure to the reverse light + after engine start and it is 10v, so I was assuming that all other "12v" (cigarette etc) will give me 10v also after engine starts. I'll do some measuring to see if I can get 12v somewhere else, if so, this might be my solution.

12V into 87 should be from a source such as the battery or fuse box, not the trigger.

[VP Electricity]

Originally Posted by jzchen

Here's a TR-7 that I found. I think a relay is cheap enough to be worth a shot before trying this though...

Relays ARE cheap. Whatever is supplying the 10V output may fry with a relay tied to it, and whatever that is is probably NOT cheap...

Originally Posted by jzchen

12V into 87 should be from a source such as the battery or fuse box, not the trigger.

Negative, Ghost Rider - the pattern is FULL.

Technic advised correctly, and YOU are telling him how to kill his battery after a couple of days of parking...

[jzchen]

Originally Posted by VP Electricity

Relays ARE cheap. Whatever is supplying the 10V output may fry with a relay tied to it, and whatever that is is probably NOT cheap...



Negative, Ghost Rider - the pattern is FULL.

Technic advised correctly, and YOU are telling him how to kill his battery after a couple of days of parking...

Okay, so I apparently don't understand something here.... I'll stay out of it!!!! Sorry.

[VP Electricity]

A relay is energized when one side of the coil is grounded and the other side of the coil sees 12V. At that point it starts drawing current.

Technic told the OP how to use the relay (which energizes with less than 12V but pulls about 80-100mA of current at 12V to energize (assuming a standard VF4 form-factor relay - "Bosch" relay to many installers)). If the transistor in question cannot supply 12V and 100mA to the coil, and it blows, that would be bad.

A. If the guy ties it to constant from the FB, the relay stays energized. You did not specify using switched or constant from the FB. This will eventually kill the battery.

B. You don't want the relay on if the amp should be off. If you tie the coil to to switched from the FB, in situations where the amp should be off, the relay stays on and so does the amp. This does not kill the battery, but is still the wrong way to run a railroad.

[jzchen]

Originally Posted by VP Electricity

A relay is energized when one side of the coil is grounded and the other side of the coil sees 12V. At that point it starts drawing current.

Technic told the OP how to use the relay (which energizes with less than 12V but pulls about 80-100mA of current at 12V to energize (assuming a standard VF4 form-factor relay - "Bosch" relay to many installers)). If the transistor in question cannot supply 12V and 100mA to the coil, and it blows, that would be bad.

A. If the guy ties it to constant from the FB, the relay stays energized. You did not specify using switched or constant from the FB. This will eventually kill the battery.

B. You don't want the relay on if the amp should be off. If you tie the coil to to switched from the FB, in situations where the amp should be off, the relay stays on and so does the amp. This does not kill the battery, but is still the wrong way to run a railroad.

Okay, maybe the circuitry inside the Relay is non-standard: He already has a condition where he is possibly pulling too much current to the trigger of his Alpine, and nothing has burned. And I admit, this may not work. I am definitely not trying to tie the coil to the fuse box, but to the positive side of the reverse light, the trigger. The other side of the coil should go to ground, right?

This is what I'm looking at:

http://www.the12volt.com/relays/relays.asp

Anyways, it says the relay pulls less than 200mA, which maybe too much as well...

[scanboy]

Originally Posted by VP Electricity

Relays ARE cheap. Whatever is supplying the 10V output may fry with a relay tied to it, and whatever that is is probably NOT cheap...

The 10v I was talking about is actually from the reverse light bulb wire (+). This is how I originally wanted to wire the whole backup camera thing. Light bulb + powers the camera and as a trigger to the Alpine monitor. The manual for the alpine monitor says that I should tie the trigger line to the reverse bulb +, except that what I thought was 12v turns out to be at 10v after engine starts. The manual and the testing with the engine off are the reasons why I believe that the monitor will need 12v in order to do a proper auto switching. That 10v power source is actually from the car, so are you saying I could fry the electronics in my car? I certainly don't want that.

Originally Posted by VP Electricity

Negative, Ghost Rider - the pattern is FULL.

Technic advised correctly, and YOU are telling him how to kill his battery after a couple of days of parking...

It's good to know that!!!

[scanboy]

Originally Posted by VP Electricity

Relays ARE cheap. Whatever is supplying the 10V output may fry with a relay tied to it, and whatever that is is probably NOT cheap...



Negative, Ghost Rider - the pattern is FULL.

Technic advised correctly, and YOU are telling him how to kill his battery after a couple of days of parking...

Originally Posted by VP Electricity

A relay is energized when one side of the coil is grounded and the other side of the coil sees 12V. At that point it starts drawing current.

Technic told the OP how to use the relay (which energizes with less than 12V but pulls about 80-100mA of current at 12V to energize (assuming a standard VF4 form-factor relay - "Bosch" relay to many installers)).

I'm good up to here, you've lost me after that. Sorry!

Originally Posted by VP Electricity

If the transistor in question cannot supply 12V and 100mA to the coil, and it blows, that would be bad.

A. If the guy ties it to constant from the FB, the relay stays energized. You did not specify using switched or constant from the FB. This will eventually kill the battery.

B. You don't want the relay on if the amp should be off. If you tie the coil to to switched from the FB, in situations where the amp should be off, the relay stays on and so does the amp. This does not kill the battery, but is still the wrong way to run a railroad.

[scanboy]

Guys, thanks for all you replies, but I'm really confused now after reading all the posts. So my ultimate question is, can I still try what Technic originally suggested without frying anything (assuming I follow his diagram correctly)?

[Technic]

Originally Posted by scanboy

Guys, thanks for all you replies, but I'm really confused now after reading all the posts. So my ultimate question is, can I still try what Technic originally suggested without frying anything (assuming I follow his diagram correctly)?

Is this reverse 10V signal that you are tapping coming from the actual reverse lights? If so there will be more than 1 amp of current in it...look for its fuse rating and that will tell you the max amps that it will be capable of handling.

If this is too complicated then go and get the PAC device for your peace of mind.

[VP Electricity]

Ditto. If it's connected to actual bulbs, then there is plenty of current capacity.

[scanboy]

Originally Posted by Technic

Is this reverse 10V signal that you are tapping coming from the actual reverse lights? If so there will be more than 1 amp of current in it...look for its fuse rating and that will tell you the max amps that it will be capable of handling.

If this is too complicated then go and get the PAC device for your peace of mind.

Yes, it is the actual reverse light. I will look for the fuse rating. I don't think your original suggestion was too complicated, just that the posts after that was kinda confusing me.
After looking at the TR7's description, seems like it's a very useful device, so I'm going to get it as a backup plan.

[scanboy]

Just in case someone else has the same problem, the relay method works perfectly. Bought a 12VDC 10A relay and wired it yesterday night, works great.