scutter
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| posted on 27/3/10 at 12:03 PM |
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Dropping voltage
Ok Lecky types.
I need to drop the 12v power supply coming out of the relay down to 5v for my VVC solenoid.
The simplest discriptions please
ATB Dan.
The less I worked, the more i liked it.
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thunderace
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| posted on 27/3/10 at 12:24 PM |
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go to maplins and buy a Resistors ,
to make it 5v
costs about 50p
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MikeRJ
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| posted on 27/3/10 at 12:45 PM |
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Are you sure your VVC solenoid is really 5v? That is pretty unusual; sensors often run at lower, regulated voltages but actuators almost always run
from 12v.
Note that a resistor can not provide a fixed voltage drop unless the current load is constant V=IR. However, for a simple solenoid, a series
resistor will be adequate as you simply need to limit the coil current to a sensible value. You will need to determine the resistance of the solenoid
coil to calculate a suitable resistor value. It may be written on the solenoid itself, if not use a decent multimeter and measure it.
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richardlee237
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| posted on 27/3/10 at 01:24 PM |
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Fit a 12v / 5v voltage convertor, cheap and simple, just make sure it can handle the current.
Quote Lord Kelvin
“Large increases in cost with questionable increases in performance can be tolerated only in race horses and women.”
Quote Richard Lee
"and cars"
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rayward
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| posted on 27/3/10 at 01:25 PM |
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yeah as said, check it really is 5v, does sound a bit odd?
i might have something lying around will check
Ray
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scutter
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| posted on 27/3/10 at 03:52 PM |
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I got the 5V information from the end of THIS thread.
ATB Dan.
The less I worked, the more i liked it.
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Dave Bailey
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| posted on 27/3/10 at 10:47 PM |
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I have an ST170 Engine in my velocity and I am using a DTA ECU.... They have a config for driving the valve....... I am pretty sure it is 12V......
I haven't tested mine yet....
Dave Bailey
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scutter
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| posted on 28/3/10 at 08:16 AM |
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I'll use 12V to start with, to keep things simple. I assume the solenoid will just get hot with 12V?
ATB Dan.
The less I worked, the more i liked it.
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splitrivet
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| posted on 28/3/10 at 05:34 PM |
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A 7805 regulator IC is the easiest way but sounds a bit odd .
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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scutter
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| posted on 28/3/10 at 07:00 PM |
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I've been out and checked the solenoid has 5V written on it!
ATB Dan.
The less I worked, the more i liked it.
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Dave Bailey
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| posted on 28/3/10 at 08:15 PM |
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You have me worried now..... I was told by DTA to use an AUx input that sinks 12V... I need to check with DTA tomorrow....it may be that they wanted
me to use this input but driv eit from 5V...
Dave B
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02GF74
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| posted on 28/3/10 at 09:13 PM |
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quote:
Originally posted by scutter
I'll use 12V to start with, to keep things simple. I assume the solenoid will just get hot with 12V?
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car electrics run closer to 14 V.
remember power = V squared / R
so by almost tripling the voltage, you are dissipating close to 9 times the power it was designed to handle.
I doubt it will last long - I would not recommend.
depending on the current, then a 7805 on a heat sink would give best regulation;
cruder method, as ^^^^ said, is resistor or use diodes to drop the voltage.
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scutter
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| posted on 28/3/10 at 09:16 PM |
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I'll switch it down
Dave, would you be able to check your solenoid? I'm pretty sure the top line had 5V in it.
ATB Dan.
The less I worked, the more i liked it.
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ss1turbo
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| posted on 5/4/10 at 08:15 PM |
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It may be getting 5v via a PWM signal originally, but some engine electrics do use 5v reference signals (TPS, temp, etc). It all depends on the
power/current requirements of the solenoid though - I've got 5V coming off a 12v/USB cig lighter adaptor, but only at about 1A or so.
Long live RWD...
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