13 replies to this topic

[olly33]

Hi,i done a search and came across these part numbers for a solid state voltage regulator,as i want to wire in a seperate smiths temp  gauge,as well as my inbuilt dash type on the nippon clocks.

Can anyone let me know which part number here i need.I know it needs to be 1 amp,10volts but all the different types are a bit confusing to me with positive/negative ones.

78LXX Series Positive Voltage from 5v to 24v with 100 Amp Output(TO-92)

L78XX Series Positive Voltage from 5v to 24v with 1 Amp Output(TO-220)

78SXX Series Positive Voltage from 5v to 24v with 2 Amp Output(TO-220)

79XX Series Negative Voltage from 5v to 15v with 1 Amp Output(TO-220)

 

 

I guess i need to wire switched 12volts supply to the Input on chip,then wire from Output of chip goes to the spade terminal one side of the gauge and the temp sender from head to other side terminal on gauge to work?  

I will mount the chip to body behind dash to earth it out also.

Cheers Olly

[KernowCooper]

The 2" round smiths gauges are fed from a voltage regulator which is 12v in and 10v out to the gauges, if you give them an ymore they read high, the voltage regulator is the type normally fitted to the rear of the central speedo.

[dklawson]

To expand on Dave's answer,..

 

You want a 7810 chip in the TO-220 size package.  (assuming your car is negative earth).  There are several makers out there for these chips.  Most have 1 Amp maximum output.  A few makers offer 1.5 Amp versions.  There is nothing wrong with the 1 Amp chips but use the 1.5 Amp chips if you can find them at a reasonable price.

 

The picture linked below from my friend Wes shows the simplest application of the chip.  When you select your chip it will list some additional input/output capacitors you can add to protect the regulator.  

 

[olly33]

Thanks for the replies. Is this the one i need?
http://www.ebay.co.u...Id=500048279129
if so i read on this forum that resistors were not needed for the low power that the gauge will use, is that correct?

[KernowCooper]

Just a thought if you do use them and start to draw 1a + then make sure the mounting lug has a path to a heat sink, to ensure the chip stays within operating temperature

[dklawson]

Do not buy the chip in the eBay link until after you have contacted the seller.  In the title he lists a 10V chip.  In the text at the bottom of the page he does not list 10V.  Make sure he has what you need.

 

As Dave said, if you buy the 1 Amp version it will help to mount the chip on a heat sink.  In the case of a 7810 chip on a negative earth car this is fortunately very easy.  The chip's mounting tab is an earth terminal.  So... you can just clean off the paint on a small spot under the dash and use a sheet metal screw to mount the chip directly to the car body.  The car becomes your large heat sink.

[olly33]

Also is it possible to use the same temp sender that goes to the stock gauge, with another wire coming off the same head temp sender to the smiths temp gauge.? Cheers Olly

[dklawson]

I don't understand your question.

 

Are you asking can one sending unit be connected to two gauges?  If that is what you are asking, the answer is "no".  One sending unit to one gauge.

 

If you are asking if you can disconnect the wire from the existing temp gauge and connect it to your new, separate Smiths gauge... the answer is "maybe".  Not all Smiths gauges use the same sending unit.

[olly33]

Yes thats what i was asking regards splitting the sender gauge wire. Did not explain it to good!
I also have another hole in my thermostat that looks like it may have a old sender unit in it, with 2 little stubs coming out of it, that i presume were wires originally?
Could i fit a new smiths sender here perhaps,so as too also keep the original dash temp gauge working from the head based sender.

Thanks for the advice, Olly

[gazza82]

Some one posted a pic a few days ago of a head with two senders .. one in the head as normal and one in the thermostat housing ..

[dklawson]

I remember the thread that Gazza82 mentioned above.  

 

Yes, if you have two separate senders you can certainly run 2 separate gauges.

 

The original Smiths electromechanical voltage stabilizer was suitable for powering 3 gauges.  If you do decide to power 3 or more gauges off the solid state voltage regulator we have been discussing it will be more important that you get the 1.5 Amp chip.

[olly33]

I also have a smiths voltage gauge wired in, but straight from the ignition feed. Does this also need to run with the voltage stabiliser in the system?
Will do a search for that other thread, Cheers.

[gazza82]

I also have a smiths voltage gauge wired in, but straight from the ignition feed. Does this also need to run with the voltage stabiliser in the system?
Will do a search for that other thread, Cheers.

 

Some do, some don't ...

[dklawson]

Voltage gauges do not connect to the voltage stabilizer.

 

A volt gauge is used to monitor the charging system.  One terminal goes to earth, the other terminal to a switched voltage source (like the ignition feed you selected) so the gauge is not powered while the engine is not running.  If  you connect the volt gauge to the voltage stabilizer, it will show the voltage stabilizer voltage all the time and will not indicate what the charging system is doing.