Some more regulator irregularities

Thread Starter

justinoberle

Joined Jun 16, 2021
36
I posted a couple weeks ago and got many good comments which I was able to resolve but I still have some initial weirdness in my power supply. I have tried LiOn AA's in series and also 1 CR123-A rechargeable with the same results. Below is the schematic of the circuit and also the graphs of the raw voltage and regulated voltage. Please let me know what could be causing this weirdness in the beginning. The sample rate is 10 seconds so 200 is 2000 seconds on the x axis. Orange=raw, blue=regulated. Below is a shorter series to show the beginning zoomed in and then a longer series to see more data if needed.
Capture4.PNG
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CompleteComponent.png
I have tried swapping the 1000uf capacitor with different varying sizes and get the same result. I don't think this is related to the regulator. Also, if I completely remove the sensor, the problem persists, so, we can conclude this is not causing any weirdness as well.
 

Papabravo

Joined Feb 24, 2006
17,310
Load and switching transients. What were you expecting?
Repeat the experiment with EVERYTHING held in RESET.
Is there some reason your grounds are pointing Left and Right?
 

Papabravo

Joined Feb 24, 2006
17,310
Hmm. I am not sure I understand how to do this. How do I hold them in reset?
You have to start by looking at the datasheet. Without a clock it is not likely the A/D converter will try to do things on it's own, but you need to review the datasheet to determine what things you are required to do to make it operational. As for the processor, if it does not have an external reset pin it may be a challenge. If it has a sleep mode where you can stop the clock and wakeup on an interrupt that might do the job. Again you have to become intimately familiar with the datasheet in order to get a handle on this problem. Or you could say, never mind, and not worry about it. Why does it concern you?
 

Thread Starter

justinoberle

Joined Jun 16, 2021
36
You have to start by looking at the datasheet. Without a clock it is not likely the A/D converter will try to do things on it's own, but you need to review the datasheet to determine what things you are required to do to make it operational. As for the processor, if it does not have an external reset pin it may be a challenge. If it has a sleep mode where you can stop the clock and wakeup on an interrupt that might do the job. Again you have to become intimately familiar with the datasheet in order to get a handle on this problem. Or you could say, never mind, and not worry about it. Why does it concern you?
Ok, I will look into the MCP3008 reset. The ESP8266 I can reset manually but I am actually running an experiment right now where I put it into deep sleep and it resets automatically every 120 seconds. Why could this resolve the issue though? Claiming ignorance.
 

Papabravo

Joined Feb 24, 2006
17,310
Ok, I will look into the MCP3008 reset. The ESP8266 I can reset manually but I am actually running an experiment right now where I put it into deep sleep and it resets automatically every 120 seconds. Why could this resolve the issue though? Claiming ignorance.
There is no issue, except in your mind. Digital devices present a time varying load to a voltage regulator by demanding more or less current over time. Different regulators respond differently to this changing demand. The point of my experiment is to confirm that it is either the one-time initialization operation of the processor and the A/D conversion, or it is periodic when the processor wakes up from sleep mode. Some regulators are better than others when it comes to this behavior. This looks entirely normal to me.
 

Thread Starter

justinoberle

Joined Jun 16, 2021
36
There is no issue, except in your mind. Digital devices present a time varying load to a voltage regulator by demanding more or less current over time. Different regulators respond differently to this changing demand. The point of my experiment is to confirm that it is either the one-time initialization operation of the processor and the A/D conversion, or it is periodic when the processor wakes up from sleep mode. Some regulators are better than others when it comes to this behavior. This looks entirely normal to me.
I see. That is good to know! Thanks
 

ericgibbs

Joined Jan 29, 2010
14,207
hi Justin,
I would expect all the 'noise' and sagging problems you are measuring on the supply rails,

The layout you have is totally unsuitable for a power supply design testing.

E
 

ericgibbs

Joined Jan 29, 2010
14,207
hi,
Long trailing Gnd and Power wiring
Bread Board socket contact resistance along the Gnd lines.

This applies all of 3 BB in use.

When you are measuring where do you choose as Ground reference.?

E
 

Thread Starter

justinoberle

Joined Jun 16, 2021
36
hi,
Long trailing Gnd and Power wiring
Bread Board socket contact resistance along the Gnd lines.

This applies all of 3 BB in use.

When you are measuring where do you choose as Ground reference.?

E
Are you asking, "where is my MCP3008 and ESP getting the ground source from?" It is on the third BB. I can change it to the first BB with the battery on it if you think it will help? It is the same ground but if their are issues with BB connectivity, as I think you are suggesting, it could help. Is this what you are saying? Just want to confirm.
 

ericgibbs

Joined Jan 29, 2010
14,207
hi J,
No, You have posted some images of the spikes etc, where exactly on the BB's have you connected the 0V/Gnd of the Test lead.?

E
 

Thread Starter

justinoberle

Joined Jun 16, 2021
36
hi J,
No, You have posted some images of the spikes etc, where exactly on the BB's have you connected the 0V/Gnd of the Test lead.?

E
It is on the negative rails of each board. Also, I have another identical circuit I kicked off about 30 mins ago, except with ONE breadboard, and it seems to be much better. The regulated voltage is working basically perfect. Here is the start of it...
Capture6.PNG
 

ericgibbs

Joined Jan 29, 2010
14,207
hi J,
I am not trying to be difficult, I would like to help.:)
The method and selection of the 0V/Gnd of the Test equipment will effective the observed 'fault' signals that you are seeing.
Consider the current that is flowing along the wires, which have some resistance value, that will produce a voltage drop across the jumper wires as also will the contact resistances of the BB.

Do you follow OK.?
E
 
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