Thread: Indoor power source for sonar unit.

Originally Posted by Hanr3

Since I will be laid up for a couple of weeks I decided I'll have time to play with my sonar unit. The question became, what do I do for power?

I thought about a 12volt riding mower battery, I have an extra in the garage. Then I thought about a 12volt power source. Did some research and decided to use the power transformer off my old Netgear wireless router.

Let me work you through the thought process on that power source.
First what are the power requirements for my sonar unit?
I went to Humminbird's web site and looked up the specifications on my HB 899CI HS SI unit. 10-20 VDC 740 mA. Your unit may be different.

10-20VDC means my head unit must have between 10 to 20 volts dc current. This is the most important number. If your power source is 24vdc you will fry your unit. The transformer will always push the voltage it is rated to provide.

740mA (milliAmps)- 1000 milli amps = 1 amp.
You need a power source that provide => (equal to or greater than ) 740 mA. 1 amp is fine, 2 amps is fine, 10 amps is fine as long as the volts doe not exceed 20.

My first option was a power supply for an old laptop set-up. It provides 19.5 VDC and 7.5 amps. More than enough power for my application, however I didn't like that 19.5 VDC. Pretty close to that 20VDC maximum. So I kept searching the house. An old cellphone charger was 12VDC, however it only provided 400mA, not enough.

Finally found the power supply for the Netgear wireless router. 12VDC, 1 amp. Perfect.

Now, I need to verify polarity of the wires coming from the power supply. Pulled out my handy dandy voltage meter, its like 30 years old, but still works. Set it to read 15Vdc, cut off the end of the cord, stripped the wires, plugged in teh power supply and attached each lead from the meter. The needle went backwards- means I have reversed polarity. Switched the wires and bingo, 12Vdc. I noticed which wire was positive. Then I plugged the power supply in upside down to see if that affected polarity. Nope, it didn't provide any power when plugged in the opposite direction. Good to know...
I crimped on some quick connectors, male on the positive lead, and female on the negative lead. Then did the opposite on the sonar power cable. Female crimped on positive and male on negative. I can only attach the power supply to the sonar power cable in one direction, prevents reverse polarity.

Fired up my sonar unit, pushed menu and put it in simulation mode, awesome. Turned it off, put in a LakeMaster Wisconsin card and fired up the unit again. again, menu and simulation mode. Map view and found the lake I want to fish at the end of the month. Now I can research the lake from my LazyBoy recliner.

Do you need a 3 amp fuse with your set up?

Originally Posted by Hanr3

Yes I was referring to your post. Again, great information.
Not sure about the Lowrance units, however Humminbird units give you options on GPS Coordinates. I think I have 4 or 5 options on format. Switch the head unit to match the source format, when done, switch the head unit back. Took me 2 hours to figure that one out. Hopefully I remember how to do it, or figure it out quickly this time. I also seems to remember that with Google Earth you can mark the spots and download them, then upload them to your unit via the Humminbird PC, and a SDHC card.

I was just dealing with different formats and sources this weekend. Thank you for your post...

Originally Posted by IceNitro

Do you need a 3 amp fuse with your set up?

Always use a fuse.

Originally Posted by Tracker123

I use this old Lambda unit for some for my projects. Have had it for years. Can control both voltage and amperage:

These are awesome units.