I did the P16PRO from this site https://www.picallw.com
because i couldn't stand anymore with the JDM… however it is not recognized by the PICALL…
I took some measurements to the pins that leave from 74LS05 and go to parallel and all are 1,5V apart from 1 that is 5V is that ok? I also observed that my 78L05 gets a little hot... also can somebody tell me what exactly each one of the leds mean? and when the should turn on?
thanks!
hi,
The 74LS05 shouldnt get hot.
Looking at the circuit diagram, the Green LED indicates that the Vpp is available and the Red LED indicate that T1 transistor is ON and the Vpp is on the /MCLR pin.
Dont quite understand what you are saying about the port pins.?
Is this a kit or DIY pcb.?
it's diy pcb...
78L05 (5V regulator) gets a bit hot...not the 74LS05
i took some measurements from the 5 pins of 74LS05 that go to the parallel connector and most of the pins are 1,5V and one is 5V.
the pcb is not exactly as in the site... (sorry that i didn't told that later..)
it's revised but i'm sure it works here's the pcb in PDF format.
although there is rectification on board...
i'm using a 6VDC supply.
hmmm the problem can be the power supply?
but i tried for short time on 12V and the regulators almost got in fire..
the power they need to dissipate is huge...
https://www.picallw.com site says:
"So here are only a few words about hardware. Supply voltage can be either AC or DC. Voltage Vdd must be between 4.5 and 5.5 V. For this purpose integrated stabiliser 78L05 (Vdd=5V) is used. It has current limitation (protection) 100 mA and with this feature protects inserted PIC from damage in case something is wrong connected. Programming voltage 13V is provided with 78L08, which has pin 2 connected to Vdd (not to the ground) and on his output there is a voltage 5+8=13V"
maybe i don't understand something correctly?
what's so badly wrong... i don't know...i'm keep looking and looking at it! what else should i do?
Perhaps we can't expect even70mA from 78L05 with 16 or 18V DC as input.
the O.P may have to measure the load current at the first instance the unit is powered in before it shuts down.
perhaps it is better to add a series resistor (or even a series zenor of say approx 9V) for lower input to 78L05.a schematic with proposed mod is attached.
I'm presuming he's using the correct buffer chip, and not substituted a non-open collector one?.
Ooooohhh... The W version may have a different pin out from the regular 74xx series chip with the power supply pins on 4 & 11 instead of the regular 14 & 7. I have an old data book here that mentions this for the 5405W which is the military spec equivalent of the 7405W. They don't mention the W version for the 7405; just the J version.without the IC and at 12VDC (as kchriste suggested...) the 78L05 gets less hot and as you can see in the following picture only the green led is turned on.
the IC says DM7405W it's a hex inverter with open collector Outputs
As the design is showing open collector NOT gates, it is better to confine to that. I fear reverse mounted Transistor dealing Vcc may have caused this issue. While it is true that the programmer is time tested, there appears no logic in allowing 13V differential between input and output. The load is ofcourse not more than 6 or 8 mA.Ooooohhh... The W version may have a different pin out from the regular 74xx series chip with the power supply pins on 4 & 11 instead of the regular 14 & 7. I have an old data book here that mentions this for the 5405W which is the military spec equivalent of the 7405W. They don't mention the W version for the 7405; just the J version.
My original thoughts:
The 7405 will draw apx 18-33ma from the supply where as the 74LS05, which is spec'd in the schematic, will typically draw 3.6-6.6ma. So that may be where some of the extra heating comes from but, if the 78L05 is still getting hot with the PIC and 7405 removed, there is something miswired.
The main issue I have with using the 7405 or 74LS05, is that the open collector outputs are only spec'd to operate up to 7V where as they are being asked to switch 13V. A 74LS06 would be the better choice as it can handle up to 30V.
The 74LS06 is an open collector NOT gate. It is also rated for the correct voltage and has the correct pin out. The 7405 in under rated and is being run out of spec. It might still work at a higher voltage, but there are no guarantees.As the design is showing open collector NOT gates, it is better to confine to that.
If you mean T2, then I don't see how this would be the problem as far as the heating of the 78L05 is concerned (With the 7405 and PIC removed).I fear reverse mounted Transistor dealing Vcc may have caused this issue.
Yes, that is a definite possibility and worth checking.Also there is a need to check for reverse electrolytic capacitors and possible failure of 0.1uF caps at the output of 78L05.
The 74LS06 is an open collector NOT gate. It is also rated for the correct voltage and has the correct pin out. The 7405 in under rated and is being run out of spec. It might still work at a higher voltage, but there are no guarantees.
If you mean T2, then I don't see how this would be the problem as far as the heating of the 78L05 is concerned (With the 7405 and PIC removed).
Yes, that is a definite possibility and worth checking.
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