Hello folks.
I want to add 5 leds and 5 on-off switches to be able to turn on and off each ESP32-cam individually and one other switch to power them all off / on at once.
My question is where to place the leds for each ESP32-cam, as they can influence the already near limit of power dissipation of the regulators if I place them at the output of the 7805.
If I put them before the regulator, they will be getting probably 16.8V (or close, from the battery pack that I decided to be using for this application instead of getting the power from the car battery), therefore I will need some resistors to limit current and also power dissipation on the resistors themselves!

What you guys suggest?

 

Hi Pys.
If you use high brightness White [3.2Vfwd] LED's You could limit the LED current to say 5mA.
So (5v-3.2v)/0.005A = 360R series from 5V

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Hi Pys.
If you use high brightness White [3.2Vfwd] LED's You could limit the LED current to say 5mA.
So (5v-3.2v)/0.005A = 360R series from 5V

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Ok, so you suggest put them at the output of the 7805 regulators, yes? I was testing them with a 560Ω (551Ω on the DMM) resistor and the 16.8V from the battery which are more around 16.24V, and the resistor still heats up a little. It's (16.24V - 3.2V / 551Ω) * (16.24V - 3.2V) = 0.31W dissipated on this resistor.
But placing the led at the output of the 7805 won't make it to dissipate even more more? We were estimating 310mA for the ESP32-cam alone in case the LED of the ESP32-cam was full ON, plus this led. It will pull more current through the regulator no?

 

Hi,
By placing them on the input to then you are not checking if the regulated +5V exists
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Hi Psy,
If your car is parked in Sunlight, remember to calculate the max allowed dissipation of the 7805's in the highest ambient internal car temperature.
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Hi Psy,
If your car is parked in Sunlight, remember to calculate the max allowed dissipation of the 7805's in the highest ambient internal car temperature.
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I might order those small heat dissipators, just in case. I also have to buy wire long enough to bring power to the ESP32-cams and to bring the power from the battery to the board! So, I might order all these at once!

I already connected all inputs and outputs and tried the battery. All outputs seems to be at stable 5.08V ~ 5.09V. Didn't tried any load yet!

 

I have nother question:
I have a few pieces of these (PH2.0) at home:
https://pt.aliexpress.com/item/10000005281831.html


Do you guys know if a AWG20 wire is ok for these connectors?

 

Well, I think I'm running into the problem mentioned by @ericgibbs.

The regulators I'm using are heating up too much even with small heat sinks I bought to them. I'm not sure it's safe to use them like this for too long!

I mean, after like 3 minutes of powering up the circuit, I can't hold my fingers on the heat sink for more than 2 seconds or so. I think this may be too much power being dissipated on each regulator.
What you guys say?

 

Hi Psy,
Do you have a final circuit you could post?
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Is it this version?

 

Hi Psy,
Do you have a final circuit you could post?
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Is it this version?

Yes, 4x that.


But the input voltage is rather 16.8V from a battery pack.
And I added individual switches to each ESP32-cam and also a general / main switch for the entire board.

I still only have 2 of the 4 switches soldered to the board and also the main switch.
But yeah, in terms of input voltage is 16.8V and the same 5V regulators. So, (16.8 - 5) divided by whatever current the ESP32-cam is sinking is probably too much for the regulators!

 

Hi Psy,
You are overrunning the heat dissipation of the 7805 at about 100% at 3.9 Watts.
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That is if you assume the ESP32-cam sinks ~350mA of current, right?
I think it's not the case here because I'm not even using the ESP32-cam flash. The 350mA is the max current of the ESP32-cam but I knew that I was going too high.

Is there anything I can do other than not using this battery pack?

But still, this power dissipation on the voltage regulator is caused only by the voltage drop the regulator must perform or by the current the load is sinking?

 

Hi Psy,
Ideally you want approx 2.5V drop across the 7805 and so at 350mA, that would dissipate 2.5V * 0.35A = 0.875Watts.
A voltage source of 16.8V will cause overheating problems.

A drop of 5V across the 7805 at 0.35A would be the heating limit, without a heat sink on the 7805
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Hi Psy,
Ideally you want approx 2.5V drop across the 7805 and so at 350mA, that would dissipate 2.5V * 0.35A = 0.875Watts.
A voltage source of 16.8V will cause overheating problems.

A drop of 5V across the 7805 at 0.35A would be the heating limit, without a heat sink on the 7805
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Ok, seems I'm doomed to not using this battery pack in any way.
Even after using those small dissipators, it seems a no go unless there is some circuit simply designed to lower the voltage from 16.8V to something closer to the desired voltage that causes the 2.5V drop on those regulators that I can place between the battery pack and the board of the 7805 regulators!

Edited;
Couldn't I use something like this:
https://www.aliexpress.com/item/4001237899672.html

 

Hi,
You could use say a 20R resistor in each supply input, rated at 5Watts, do the sums.
Or a common high basic power transistor pre regulator to drop from the 16.8V to 10v.
Your system is only 30% efficient.
Look on eBay or Amazon for 12v/24V input switched regulator, that will give 10v out.
Ask if you need help.
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Hi Psy,
A module of this type should be OK, you may find a lower power version, if required
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https://www.amazon.co.uk/JZK-Adjust...&sprefix=dc+to+dc+smps+modules,aps,70&sr=8-17

 

Hi Psy,
A module of this type should be OK, you may find a lower power version, if required
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https://www.amazon.co.uk/JZK-Adjustable-Converter-1-25-36V-Regulator/dp/B09TT1Q739/ref=sr_1_17?crid=34UXH5WGBPN2G&dib=eyJ2IjoiMSJ9.2O8OlVrq1akQvAihnzQM9UJT4_skp0NwO70GPSIfeBLj1glJJ1Ca-y0MgOzGbY2UgTN8tLA1PsZnZIHHUq0-OokR2lA5sKJzmGmYayXG4QkpwrU-ljyddYEcrb33M5kU2uCy2a2DEnSwNoamTLJoiuKQRWgtN_fEfJI7Q56atlcyC6KfATrYc1CSvU3YV4Rge-g5j9abo4JIf1vz12bFqDBOjIaNbvTDaZHGFBWe3YzIL8Ssd6xOdFM6QzF1wQQRtCgE02ME3QJNjiNPz7dcJDoUI-Drl1ICPi0aPZrcOI4.0glkPIv9Tq8NcSP6CQ_7o_T2K9q8sc2TDhCdCOLb0vU&dib_tag=se&keywords=dc+to+dc+smps+modules&qid=1713809766&sprefix=dc+to+dc+smps+modules,aps,70&sr=8-17

That one says currently unavailable.
But I'll try to find some other one in aliexpress or so. It's probably an easier solution and cheaper than the 20R 5W resistors. In fact I have 5R 5W and 4R 5W resistors here but I think I'll go with the buck converter!

 

I just got the buck converter and somehow I can't get it to lower the voltage under 15.86V while the input is at 16.10V
I can get it to 35V+...

So, I guess this a step up converter?? It just doesn't go under the input voltage.
I guess the description of the item I purchased is incorrect and I bought a different item. *uck this sh*t. I'm mad.

 

Morning Psy,
Do you have a photo image or a link for that PSU.?

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Morning Psy,
Do you have a photo image or a link for that PSU.?

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You mean the converter or the power source for the converter?
The converter I bought is this:




I also have a small video showing that rotating the rpot doesn't lower the voltage under the input voltage. But the file extension is not allowed here!