I haven't done anything like this in years and never had all the theory anyway. The circuit below is for an intervalomer using a ProMini which has been lying around for a long time, and with an ESP-01 operating in setup only. It was "designed" from scraps of information with parts from Jaycar over the hill. The perf board for the whole thing is getting seriously crowded, but I am wondering about putting in a 100uF as well. There is just enough room for that. [power and levels]

The circuit looks like okey. Is it working in its application? Do You mean to upgrade both 10 uF to 100 uF? It can't be wrong but what about adding some 100 nF ceramik, to kill eventual spikes, as well?

Better to use the EN pin of the ESP-01 to switch the ESP on/off (HIGH is 'on', LOW is 'off'). Note that you also need a 2k:1k divider there. Leo..

Thanks for your comment.... No, I was wondering about adding a 100uF to the 10uFs already there, and indeed I thought about a 200nf that I have lying around. I suppose it might be better to replace one 10uF with a 100uF. Nothing has been actually made yet and I am just seeing if I can squeeze it all onto a 24x30 perf board.

[image] Wawa: Better to use the EN pin of the ESP-01 Well, there you go, I have never had an ESP-01 and had no idea about the EN pin, I now guess you are alluding to pin 4, as shown. I will check Pieter's ESP Page. Thank you [ESP-01]

[image] Nick_Pyner: I have never had an ESP-01 Never used one too, but I do use bare ESP-12 modules, which also have that EN pin. Leo..

Thanks for the comments. This is the revised arrangement for anybody that might be interested. [power and levels 2]

I believe both RX and EN "idle" high. If that's true, then the resistor dividers might sink a couple milliamps most of the time. If either pin is pulled high internally, then a series diode might be a better choice. The Pro Mini could bring either line low, but not high. And even if you had to add an external pullup resistor to 3.3V on those pins, along with the diode in series, it still might be a good solution. Well, if the radio is going to be off most of the time, then the divider would be fine for EN. Not sure about RX. If you were starting from scratch, I think you would run the Pro Mini at 3.3V, 8MHz, eliminate the boost converter, and get a better 3.3V LDO with a much lower dropout voltage. Maybe even run it all on a 3.0V LDO if the ESP would deal with that ok.

Suggest you use two converters. BTW, You might want to look at removing the potentiometer. [image] Share tips you have come across General Electronics In situations where an accidental change in a potentiometer setting can cause catastrophic problems, change the potentiometer out for fixed resistors. Make a resistor substitution board ahead of time to use it to determine what the values of these resistors should be. All the standard resistor values (SMD 1026) have been placed on the substitution PCB. One end of all the resistors are common and would represent the wiper on a potentiometer. Female headers on the other side of the resistors w… [image] Boost/buck converters come in small form factors. 3.3V Step Down/Up [image]

Well, I'm glad I asked before I got too deeply into this... I should have been more forthcoming: This project is an intervalometer with clock for use in astrophotography - specifically, ISS transits. A lot of the stuff, 5v ProMini, LEDs, 7221s are already lying around but I haven't really done any of this power supply stuff since about the invasion of South Georgia so I guess there are slicker ways of doing this and certainly wondered if I really need an adjustable pot. Further, I guess I can expect more modern modules to have the requisite caps on board. [image] ShermanP: along with the diode in series, ..........then the divider would be fine for EN. Not sure about RX. I'm not sure what this involves. The radio is off virtually all the time. It is just there to ensure the DS3231 is truly up to scratch. The only alternative to the usual 1k/2k divider I know of is with a BS170 MOSFET [MOSFET level converter] but I have never used it. It didn't occur to me to use it now, but this might be the time, even if only for ESPs Rx. [image] LarryD: Suggest you use two converters. OK, I found one which looks like yours and specifically for ESP8266 even though it is coy about the current. And another to deliver up to 480mA @ 5v. Both to be in parallel on the 18650, rather than the up/down daisy chain I had before. Even though I think I only have one to hand, I am tempted to use two NMOS, just for the elegance and perhaps greater efficiency. Not that that is so important. The ESP will only run for a few seconds, the display a few minutes, and the whole thing for no more than a day. [vertys and nmos]

Confused.. Why a DS3231. The ESP-01 has a crystal clock. Do you need "time" or "local time". The ESP-01 can do that when booting near a router. Why WiFi anyway. What is "everything else". Can't it run off 3.3volt. Then you could use a LiFePo4 battery, so you don't need an LDO. Why the ProMini. You already have a processor. Leo..

Care to comment on my 5v and 3.3v power supply?

Projects General Guidance

LarryD January 1, 2023, 6:54pm 9

Suggest you use two converters.

BTW, You might want to look at removing the potentiometer.

Boost/buck converters come in small form factors.

3.3V Step Down/Up

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Care to comment on my 5v and 3.3v power supply?

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