Grounding?

[Walrus]

I'm planning on using a UCC383TDKTTT-5 low dropout regulator in my mod. The center 'leg' is for grounding... but I don't see how you can ground a portable device. Would this still work if I don't connect anything to the ground? Is there something I can do to ground it? Am I setting myself up for a fail?

 

[CaSHMeRe]

Walrus, you can always *bolt/spring* it assuming it can come in contact with the body of the device itself. Do you have a picture of it?

 

[planetofthevapes]

Walrus, use your negative for the ground. You only have to use the middle prong. don't worry about that top tab. I know this is the way to do it because I did it, no shorts or nothing...works wonderful. There is nothing to ground to other than the negative. Works perfect, I promise.

 

[planetofthevapes]

Here is an example, the wiring schematic for my last mod. Yes I know 9v has barely any mah, I was just testing out a theory last weekend with the 5v voltage regulator. Was just fun!

Oh, and the purple dots are just where I soldered.

 

[Richie G]

Walrus, you can always *bolt/spring* it assuming it can come in contact with the body of the device itself. Do you have a picture of it?

>

I think this is the one ---

 

[Laredo7mm]

walrus, planetofthevapes is correct. Just connect the GND pin to the negative of the battery. If I remember correclty this is for your double 18650 mod, so you should be able to connect ground to the flash light body.

The tab has no electrical connection, but is used for heat dissipation. Check out page 9 of the spec sheet from TI, it talks about thermal design. It says:

...the linear regulator and heat sink must dissipate power equal to the maximum forward voltage drop multiplied by the maximum load current.

The chip has thermal shut down protection, so if the temp rises too much, it will not turn back on until the temp goes back down to 20 degrees celcius.

Richie G, that is the wrong chip. Similar, but the chip in question does not have the center leg cut.

 

[Cellmeister]

Yes The Gnd Connection Goes to The Batt Neg Terminal or Body of Tube If Thats Gnd (it should be wired that way).

FYI: Some Of The 5 Volt Voltage Regulators Require 8 Volt Input or They Will Not Function.... But I Assume You Already Checked That Prior To Purchase.

Hope That Helps

 

[Nuck]

Yes The Gnd Connection Goes to The Batt Neg Terminal or Body of Tube If Thats Gnd (it should be wired that way).

FYI: Some Of The 5 Volt Voltage Regulators Require 8 Volt Input or They Will Not Function.... But I Assume You Already Checked That Prior To Purchase.

Hope That Helps

That chip rocks. Laredo posts links to a slightly different version in another thread. It has a low drop off of less than 1/2 a volt.

 

[Cellmeister]

That chip rocks. Laredo posts links to a slightly different version in another thread. It has a low drop off of less than 1/2 a volt.

Yes, Thats Why I Said "SOME".

Thanks For Your Input.

 

[planetofthevapes]

walrus, planetofthevapes is correct. Just connect the GND pin to the negative of the battery. If I remember correclty this is for your double 18650 mod, so you should be able to connect ground to the flash light body.

The tab has no electrical connection, but is used for heat dissipation. Check out page 9 of the spec sheet from TI, it talks about thermal design. It says:



The chip has thermal shut down protection, so if the temp rises too much, it will not turn back on until the temp goes back down to 20 degrees celcius.

Richie G, that is the wrong chip. Similar, but the chip in question does not have the center leg cut.

I didn't look into the particular regulator walrus is using...I just went by the one that I had in my hand. The tab on top and the middle post were both labeled as ground. I only connected one. That is interesting information though, I will check to see if mine heats up and works similarly.

 

[Walrus]

Thanks for the replies, guys. As for grounding to a tube... well, at this point I don't know that I'll have a tube. It may end up being a Radio Shack project box. I'm waiting for the custom battery holder I ordered to arrive so I know what my size limitations are.

The minimum voltage in on this chip is 5.45v, max is 9v. I'm planning on using 2 18650s in series, so I should be seeing around 8.4v at full charge.

 

[Nuck]

Thanks for the replies, guys. As for grounding to a tube... well, at this point I don't know that I'll have a tube. It may end up being a Radio Shack project box. I'm waiting for the custom battery holder I ordered to arrive so I know what my size limitations are.

The minimum voltage in on this chip is 5.45v, max is 9v. I'm planning on using 2 18650s in series, so I should be seeing around 8.4v at full charge.

Man..that thing is gonna be a peace pipe!

 

[Walrus]

Man..that thing is gonna be a peace pipe!

lol hadn't thought of doing it that way. The custom holder I ordered has them wired in series, but side to side. It'll be more like holding a wall wort to your face

 

[bzlytbeer]

Just a question. I ordered on of these from Texas Instruments, but was in Radio Shack the other day and saw the 7805 Voltage Regulators. Are these basically the same thing?

 

[firhill]

Just a question. I ordered on of these from Texas Instruments, but was in Radio Shack the other day and saw the 7805 Voltage Regulators. Are these basically the same thing?

Courtesy of Mogur(from another thread).....

One problem, though, is that the common regulators drop about 2.5v, so a 5v regulator would start dropping the output voltage when the cells output fell to 7.5v. The ultimate solution is to get a low dropout regulator (only a .5v drop between input and output).

The 7805 is a "common" regulator

The TI one is a 'low dropout voltage" regulator.