Cheap temp probe

[RAHFISH]

Folks,
First a sincere thanks for all the great info I have gotten from this site, hope to put it into more use as time and family will allow.

Now to the probe--as you can see, it is made from a $20.00 temp unit from MinnKota. The spool is from a local tackle shop and holds 50' of cable. The temp probe is inside a 1/2" short threaded section of PVC with screw on end caps. The probe is in one end and the wiring (zip cord) are enclosed in epoxy and then the wire splice is inside the pipe cavity. I wrapped a short piece of pencil lead around to increase the weight so it was stable underwater and would sink at a good rate. Pretty simple!

A few details---be sure to watch the polarity on the factory wiring and the zip cord---fifty feet was all I wanted but I hooked it up to a 100' roll and it worked fine on the bench---be sure to use velco to attached the reading unit to the spool as you have to get to the back of the unit to shut it off and change batteries---use a good zip cord that has the inside wiring melted around the wires as it is extruded, this keeps air space out of the wire and insulation--response time is good but I let it set for a time at each level I measure (normally 5' or 10' intervals)

I have used it several times for the last couple of years with no problems. If I can find the time, I could improve the "roll-up" feature to be faster than my slowly twisting the spool.

Hope it works for you, let me now if you have any questions---RAHFISH

Camano Island, WA

 

[SuperD]

How much for a working unit?

 

[RAHFISH]

Not sure if I understand the question, but this one cost me about $35.00 with the $20.00 Minn Kota temp unit and $15 or so for the wire, pipe, epoxy, etc.

I did want to comment on the difference in the readings you can see on the digital readout screen---the middle reading is the ambient reading where the readout unit is located, the bottom is the readout for the probe. I had been fiddling with the probe before the shot and may have elevated that temperature.

In additon, there was a small difference between the two readings when measuring the same air temp. I used a precision thermometer and water bath to check the calibration of the probe and it only varied a few tenth's of a degree over the normal temp range you would see in a lake. Certainly close enough to get good readings.

Good luck---RAHFISH

 

[kokenut1]

did you just add wire to the probe? how did you lengthen the cable? looks nice.

 

[RAHFISH]

PM sent

Sorry to be so long in getting back to you, I was back east on a family trip.

You are correct, I just added a 50' piece of good quality (extruded-to cut down on air spaces) to the wires that I had cut on the MinnKota temp probe. Very simple but be sure to watch the wire polarity. Just keep the wires marked when you cut them on the temp unit to splice in the new zip cord. Normally the zip cord wires will be brass toned on one wire and kinda silver on the other.

Also, the MinnKota wires are very small so use caution as you can tear out the small threads when you remove the insulation.

Let me know if this is not clear and we can talk again---RAHFISH

ps--As I said, you can go longer on the wire if you need to but will take a bigger spool

 

[kokenut1]

Well I made one. Got the water temp only model for about $6 on E-Bay and had a spool of speaker wire laying around, I think I got a total of about $10 in it. Haven't had time to test it in the lake yet but it is reading fine. I made a small down rigger so I could wind it up, it works good on the bench, I'll just clamp it to the side of the boat. Can't seem to figure out how to post the pictures though. Thanks Rawfish for the idea, I'd like to send the pictures to you by E-mail if possible.