I have been trying to use ebay voltage levellers for a project using ESP-01 wifi interface. So far I have tried 4 and they all give odd readings and don't give me 3.3 v from 5v input.
The last unit gave me 2.2v on the LV side for 2 mins then changed it's mind and gave me -0.4v.
Connecting 5v to the hv pin puts 5v on all the other high side pins except the ground pin. This seems awfully strange. All 4 of the boards I have purchased do the same thing.
Am I missing something, has anybody had the same thing happening with these ebay boards.
If the line isn't connected they will give you 3v3 (or whatever you connect to LV) and 5V (or whatever you connect on HV) on the channels. Only if you GND one side, the other side will also get grounded.
So wire it up, 3v3 to LV, 5V to HV, common GND to GND.
Now you should have 3V3 on all LVx pins and 5V on all HVx pins.
vsl:
The last unit gave me 2.2v on the LV side for 2 mins then changed it's mind and gave me -0.4v.
Well, clearly it did not give a negative voltage so there was something wrong with the way you measured it.
To use an ESP-01, you connect a diode with cathode to your 5 V device output and anode to the ESP-01 RX pin. The ESP-01 TX pin you simply connect to the 5 V device input. As in this circuit:
You might need a 4k7 pull-up to 3.3 V on the ESP-01 RX pin.
my bad!, my apologies chaps, I was under the impression from reading various web reports that I could power the ESP-01 from the LV on the board.
I obviously need to pay more attention....I also thought the hv1,hv2, lv1,lv2 would sit at ground and just raise or drop the signal voltage when received.
And to save you another pitfall: no, you can't use the 3.3V output of the Arduino either. It just can't provide the power the ESP-01 processor needs (which is 100-200 mA when transmitting; way more than the 50 mA the Arduino has available).
vsl:
my bad!, my apologies chaps, I was under the impression from reading various web reports that I could power the ESP-01 from the LV on the board.
Well now, that is quite fascinating as if you had used this version of the level converter, it does provide you with a 3.3 V regulator to power the ESP-01!
Indeed the description is not clear (which is perfectly normal for an ebay listing).
That 5-pin part on the right of the PCB is almost certainly a regulator indeed. It comes with two capacitors (the brown blocks). Unknown type, it's a very small package so probably can produce no more than about 200 mA. Can't tell for sure without knowing the actual part number.
The two black three-pin parts are MOSFETs, fair chance it's the BSS138. The four black blocks marked 103 are the 10k pull-up resistors.
The small black part on the right of the regulator I can't identify.
For the ESP I normally use the AMS1117-3.3 regulator. A bit of an oldie maybe but does the job well, delivering up to 800 mA with a minimum drop-out of about 1.0-1.2V so perfect for 5V to 3.3V regulation. As long as this regulator can deliver at least 200 mA you should be fine, it may not be able to handle this continuously (due to heat) but the ESP only needs this current as bursts, drawing much less most of the time.
i had a look at that and the description only says
3V3 connected 3V system power supply
and no mention of a voltage regulator.
would the presence of a voltage regulator assume one will get 3V3 from the 5V supply side ?
I agree with you and wvmarle, it is not clear. I think wvmarle is right about the parts. The small black part on the right is most likely a ferrite bead or diode. It would be possible to follow the traces, and verify with an ohm meter some of the traces, and make a schematic of the board. And an ohm meter would let you figure out if the small black part is a diode. You can follow the traces on the board, since most are visible, and see the output of the regulator goes to the 3V3 pin. As wvmarle points out, it would not provide much current. I think little modules like this are pretty nifty. I did not know about this one before Paul__B pointed it out, thanks Paul. alice1101983 has been around a long time on eBay selling interesting stuff.
I was thinking of a diode as well but can't think of how that'd be used in the circuit, a linear regulator doesn't need this. Not likely to be an inductor, definitely not a ferrite bead (which goes around a conductor).
