HiLetgo 10pcs Mini RS232 to TTL MAX3232 to TTL Level Converter Board Serial Converter Board RS232 to TTL Serial

Works fine. I was a little leery after reading some reviews, but read enough of them to avoid the potential issues. I'm using it to add 2 serial ports to a Raspberry Pi.Things to keep in mind:1) There are TWO converters, one on each face of the board. There's not enough room on the chip side to label which end is TTL and which is RS232 (did I mention it's tiny?), but it matches the other side which is clearly labeled.2) If you're not using the second converter, don't leave the input floating or it'll overheat. See other reviews for how to add a pullup resistor.3) I had no trouble attaching flexible 28 gauge wire to the small solder pads. I could see if you tried attaching larger or solid wire, or a component directly, it could be dicey.4) Some reviewers complained about mounting it, but it's easy if you attach all 8 wires first. Then connect power using the through-holes (I snipped leads from diodes for this), so the whole thing is suspended over your main PCB. I added a 3rd lead to the other side to secure it better.So don't let the other reviews scare you. It works, and good luck finding anything more compact or cheaper.

Way too much power draw on every one. They get so hot they’ll give you a burn. On each board the + pads are common as are the - pads and none of the pins are shorted.These are so difficult to work with I wouldn’t rate the very well even if they worked.

Some of these overheat. The problem is that they use a substitute MAX3232 chip that is missing an internal pull up on pins 9 and 10. Only half this chip is used on this board and pin 10 is not connected and floating. The result is that the chip can oscillate at a high frequency and overheat. The solution is to add a pull up resistor to V+ on pins 9 and 10. Any value from 20K to 400K will work. As only 1/2 the chip is used you can connect 9 and 10 together and that makes adding the resistor much easier. After the added resistor the boards seem to work fine.

These work well and do not heat up, however, there is a key point that the seller needs to emphasize - these devices provide *two* RS232 (TX, RX) pairs. Each pair is on one side of the PCB - this is the reason for the pads without holes. The other users that talk about drilling through those pads are shorting two different channels and make the channel drivers fight each other, resulting in higher heat dissipation.Note to seller - personally, I would have preferred if the TX/RX pairs used four through-hole pads on each side and the connections to GND and Vcc were on the bottom as pads you solder to. Or, even better, one can extend the PCB by 2.54mm and have two more through-hole pads.

When I received these, they were not separated but the PCB was scored so that I could break them apart. I took one off (they are very tiny) and soldered it into my circuit. I started testing the transmit lines (TTL -> RS232 voltages) and my receiver (an RS232->USB adapter) did not decode any of the characters being sent. So then I started looking at the RS232 output data line with a scope and it looked like this thing was operating more like a buffer than a level converter. The output voltage was between 0v and 5v, while the low voltage should be below -3v. So then I looked at the V+ and V- pins on this MAX3232 chip on this board. The V+ was at 4.5 volts which isn't great but is at least within spec. The V- pin was only at -2v, so clearly something is wrong with the chip or the circuit which caused this problem. Then it occurred to me that since all 10 of the boards were still stuck together from a larger PCB, the manufacturer almost certainly did not test any of these. So some of them probably work and others don't. I don't have enough time to painstakingly re-solder different boards into my circuit to try and find one that works, so these things are not terribly useful to me. I would rather pay more to get one which is more likely to work out of the box.

First of all, these parts are very easy to use and to understand if you just look at the boards for a few seconds and use your brain.One side of the board shows which end of the board has TTL and which end has RS232 signals. If you flip the board over, there's no label to help you but, just look at the other side and follow the same directions and all will be fine.Another reviewer added a picture that was helpful for making my picture from. His seemed to have text that didn't match his photo. Anyway; I added an amended photo to mostly show that, if you flip the board over, and see no "TTL-RS232" text, the line on the chip, showing the direction for pin-1 is on the RS232 side. Again; Just look at it and use your head.As others noted, the VCC and GND are exactly that. They are a pass-through of supply voltage. There should be no reason to see "-2 volts" on the "-" side of the connection. Supply voltage ground is "-" and VCC or "supply voltage input" is "+". They are connected together to pass power through the board, which I found helpful while making a cable with the conversion built-in.As for the value; Just try to buy a MAX3232, and the caps, to then solder onto your own board for the price these things cost. For the money, I will absolutely use these boards in my product. And I use both channels of the MAX3232.I dinged them for one star because the traces are very delicate and you need to avoid thinking that they will support a wire connection of more than maybe 30 AWG. Having said that, I used a stranded 28 AWG connection and "potted" the connections with hot melt glue to act as a strain relief.Would it be nice if they made all of the connections plated through holes instead of surface mount pads? Absolutely! They could make the board a little bit longer to offset the connections and, while they're at it, make the connections match in either direction. I'd pay double for that feature.