WiFi power issues

After a fairly extensive debugging session, I've finally produced the following error message:

ets Jan 8 2013,rst cause:1, boot mode:(3,6)
load 0x40100000, len 23620, room 16
tail 4

which I believe means the ESP8266 has browned out and reset itself due to lack of power.

Cut down version of the code:

http.request(httpOptions, function(requestResult) {
  requestResult.on('data', function(data) {
    digitalWrite(A15,1); // FC Close

    console.log(data);
    var written = f.write(data);
    f.skip(written);

    digitalWrite(A15,0); // FC Open
  });
});

This happens fairly regularly if the file I'm fetching is big enough. I've hooked my SD card power up to an external voltage regulator so the only thing being powered by the Espruino is itself.

Gordon can you give this a go at your end and see if you can replicate?

Hardware FC is enabled using

'AT+UART_CUR=115200,8,1,0,2\r\n'

file is fetched over HTTP, about 46kb. SD card is at default baud rate. The problem occurs at different stages of the file transfer, but it happens almost every time for me.

Can you think of a board trace I could cut and supply voltage to the ESP8266 myself from another external voltage regulator? Problem with that is the ESP8266 needs a capacitor across VCC and GND otherwise you get these power issues...

Oh I've actually just tried it with the writing to the SD card commented out and I still get the issue.