Resistor Hack for Innotek IUC-4100 & Innotek IUC-5100

The biggest drawback of the Innotek systems (Innotek IUC-4100 and Innotek IUC-5100) is that you cannot adjust the correction level of each collar separately. There is a little workaround that involves running a resistor across the probes of the collar to reduce the correction level on a collar.

First, get the collar and unscrew the two probes to expose the two mounting threads underneath. Now wind one leg of the resistor around each mounting thread. Finally, screw the probes back on to lock the resistor into place. The resistor reduces the amount of correction delivered to the dog on only the collar is affixed to. It does this by creating a parallel path for the current to flow.

Using a 33K ohm resistor, you can reduce the correction level on the collar by 50%. Using a 5.6K ohm resistor, you can reduce the correction level on the collar by 75%.

One thing to remember is that when you recharge the collar, remove the resistors before placing the collars in their charging cradle. If you forget, the collar will not charge properly. This makes the hack a bit of a pain. So consider a system with the independent correction built straight in. If you want something rechargeable, the Dogtra EF-3000 would be a good choice. If you don’t mind having a disposable battery, the PetSafe Stubborn, PetSafe Little Dog and PetSafe Deluxe combination is good because it allows you to mix and match collars between systems.

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{ 10 comments… read them below or add one }

Daniel February 24, 2015 at 2:36 am

Just a comment.
The parallell resistor hack doesn’t decrease voltage. It decreases the current going through the skin, as the current path gets divided in two. The voltage stays exactly the same.
If the resistor were in series on the other hand, i.e between one of the prongs and the skin, then it would decrease the voltage. It would decrease the current in this case also because the current path through the skin suddenly have added resistance.

ADMIN – Hi Daniel. Thank you for your comment. We recommend using the Innotek IUC-4100 (No longer available) & Innotek IUC-5100 underground dog fence systems (Limited stock item) without resistors. Installing resistors will void the One Year Non-Transferable Limited Warranty.

Penny Bergstrom March 17, 2013 at 5:53 pm

We have two dachshunds 16 and 13 lbs. Is this the best model I don’t like that the small dog system needs new batteries one a month especially with two dogs.

ADMIN – Hi Penny,

If you are looking for a lightweight rechargeable for the dachshunds, the PetSafe Ultrasmart and the Dogtek EF-6000 would be two good choices.

Meg October 29, 2012 at 12:35 pm

Hello, We have 3 dogs, a 25 lb beagle, a 60 lb mix, and a 105 lb German Shepherd. We are interested in the IUC 4100 system, but worry the settings required for a fired up to kill a squirrel German Shepherd, would injure our beagle (whom follows him everywhere). Also, do all of these systems required lines that need to be buried or are there wireless ways to set boundaries as well? Our lot is 3.5 acres, and winter is fast approaching, so the less digging the better. Thanks!

ADMIN – Hi Meg, with your mix of dogs and containment goals, we’d recommend a PetSafe Stay + Play fence. You can add any number of collars to the system and allow set individual correction levels for each dog. The major limitation is that the system will create only a circle shaped boundary covering a maximum of 3/4 of an acre.

Laura December 15, 2011 at 11:55 pm

Hi! We have a just-over-40 lb pit mix and a 20ish lb terrier mix 8-9 month old puppy who our vet thinks will top out at about 25 pounds. Would you suggest a resistor initially for the pup, or if she’s just under the 20 lb difference, will the Innotek IUC-4100 collar work as-is for her without shocking her too much? We’ve reviewed your info and think the Innotek is the right system for us. Thanks!

ADMIN – Hi Laura,

Pit bulls often require a bit more correction than other dogs. That and the 100% size difference make me think it is likely the two dogs will need different correction levels. I would start by setting the Innotek to medium and using the 50% off resistor on the Terrier’s collar. As always, dogs are individuals and you should observe the dogs and change the correction level if it is either too high (dog is getting overwhelmed) or too low (dog is not immediately refocusing on the correction). But, I think it highly likely that the resistor will be necessary to lessen the correction for the Terrier.

Michael July 13, 2011 at 4:25 pm

I’m assuming that if I try a higher ohm resistor that it may allow enough voltage across the skin leads to cause a shock when the system is in “low” mode. Is this correct?

ADMIN – Hi Michael,

The higher ohm resistor, the higher the correction. Low ohm resistors will have a higher correction. (The higher the resistance, the less voltage will go across the resistor and the more that will go across the skin)

Michael July 13, 2011 at 3:32 pm

I tried this hack and it did not work. I bought 33ohm and 5.6ohm resisters from RadioShack, both were 1/2 watt rated with 5% tolerance. The 33 ohm resister (tried twice) produced no shock whatsoever even when the fence was delivering the high level shock. The system itself is set to “low”, but the collar delivers no shock at all, even when right next to the line and beeping like crazy (as tested on my own arm). What am I doing wrong?

ADMIN – Hi Michael,

You need either a 33K (33,000 ohm) or a 5.6K (5600 ohm resistor). A 33 ohm resistor and a 5.6 ohm resistor have very little resistance – hence almost all the voltage goes through the resistor and almost none through the dog’s skin. You would feel very little if you used the 33 vs 33K ohm resistor.

Wendy May 28, 2011 at 3:11 pm

I have two dogs: one a 100 lb chocolate lab (who is mellow and tends to learn relatively quickly. Then I have a 45 lb boxer (she is full grown) who is the ‘hyper’ one of the two and tends to take WAY MORE to train. I am wondering if this would be a good solution for both of them??? I am also nervous that she (the Boxer) may need the full strength. Thoughts? Thanks!

ADMIN – Hi Wendy,

The Innotek IUC-4100/5100 will work fine with a Boxer and a Lab. I would be surprised if even a hard headed Boxer required more than the medium setting. While hyper, they usually are sensitive to correction. Unless you have had any experience to the contrary using some other form of correction (like a remote training collar), it is very unlikely that you will require something stronger.

Sarah February 23, 2011 at 10:25 am

Would this workaround be effective for my 11 lb. chihuahua-mix? She isn’t your typical chihuahua- she has a thick neck with plenty of fur and this system appeals to us more than others. We have a young doberman that has the potential of weighing over 100 pounds when full grown, so there is a great size difference between our dogs.

ADMIN – Hi Sarah,

Yes. We have a resistor we can send that will reduce the correction level by 75% and would be effective for your chihuahua mix.

Brian Caine January 30, 2011 at 11:19 am

Based on your description of this hack, I get the impression that this resistor is an add on, as opposed to the replacement of an existing resistor. Is this correct?

I suspect that my dog has a high pain tolerance, where the stubborn might be a better option, unless I could just up the juice a bit by replacing the standard resistor (if it exists) with a lower resistance. If possible, this might give me stubborn dog results with the 4100 system.

ADMIN – Hi Brian,

Correct, the resistor is an add-on, not a replacement for a resistor already in place in the IUC-4100 collar. There is no way to use the resistor to increase the correction, only decrease the correction. If you wanted something stronger then you would want to go to something like the PetSafe Stubborn.

Joe Steidl August 8, 2010 at 7:02 pm

Thank you for this great hack. I looked for a solution for the strong correction my Boston gets. I actually strapped the collar on my leg and walked near the fence I installed. Wow! I just couldn’t put the collar on him again. He is usually very well behaved anyway. This will make it all easier. I will check around for the resistors.

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