Can a 9V supply enough power?

So I'm thinking that my communications problems with a target PIC16F877A may be because I'm using a 9V through a 7805 (it may even be a 78S05) to supply external power. I can read, apparently, but not write or erase; could it be that the 9V can't pull enough current?

Almost no current is required, a 9V PP3 type battery is fine.

However, you need more voltage for high voltage programming, what are you trying to do?, and with what programmer?.

Hey Nigel, thanks for the speedy reply.

This is a bit of an ongoing issue. I'm using a JuneBug to program a target PIC16F877A. Currently we were just trying to write some arbitrary code to it to make sure communications is working - and READ and VERIFY in PICKIT2 and MPLAB seem to work, but any time I attempt to WRITE or ERASE/BLANK CHECK the PIC, I get an error.

Initially I thought that the JuneBug wasn't able to supply sufficient power, so I have since attempted to supply an external 5V with a 9V battery and 7805. However, it still isn't working. We're going to be trying a different PIC16 this afternoon to see if the PIC is somehow the issue.

Any other ideas? (This is a university project)

Writing and erasing requires about 13V, this is supplied from the Junebug, regardless of external power or not.

Is your circuit correctly designed to allow ICSP?.

Picture attached, as given to me by another helpful forum member. This is the entire circuit at the moment, with VPP supplied as 12V by the Junebug, and VDD coming off the 7805 and also connected to the Junebug, likewise with VSS tied to ground, and then data (PGD) and clock (PGC) coming from the junebug.

Note that both VDDs and VSSs are jumped together.

Is this circuit sufficient?

Edit: These ofc ourse correspond to the 5 pins on the JuneBug ICD - VPP to VPP, VDD to +5V, VSS to GND, data to PGD and clock/clk to PGC.

So you're just using it as a programmer, not doing ICSP?.

That is correct.