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bs250 posed issues, that forced me change to batter device. For n mosfet, you can re orient and use 2n7000 be sure that the artwork follows the type of make you choose. otherwise, bend pins and mount
No wonder many custom made do lite version. the programming on the GO without PC is rarely use.
I done create one, but able only to program naked PIC. if connected with board that can program PIC using PIC KIT 2, it come out with VDD level error or VDD must 3V to erase and program(if connect to 5v).
Yes. These problems come up.
the issues are listed either in read me file or trouble shooting of the pickit2 user guide.
the number of caps used on target board wont allow the Vdd to raise in time wrt Vpp
Secondly, if the Pgdata and pgclk pins are also used in target, we need to use them only after a resistor of specific value in series. The ICSP should be before that se resistors.
Little reading of pre conditions for use as icsp would reveal the and you can solve.
All the best Ragens
Yes. These problems come up.
the issues are listed either in read me file or trouble shooting of the pickit2 user guide.
the number of caps used on target board wont allow the Vdd to raise in time wrt Vpp
Secondly, if the Pgdata and pgclk pins are also used in target, we need to use them only after a resistor of specific value in series. The ICSP should be before that se resistors.
Little reading of pre conditions for use as icsp would reveal the and you can solve.
All the best Ragens
for higher current from USB socket. perhaps you have to manage the software driver inside laptop /desktop.
My observation has been, that from USB sockets are not able to deliver that much current. and the Vdd adj circuitry , unless you use the rail to rail op-amp and a good P-mosfet, you cant expect proper current. likewise Voltage switching using the dual complementary mosfets ( later computerman9 called them as U5p and U5n) have also the capacity to deliver. in our experiments we starred using BS170 or 2n7000 for n mos and Bs250 for p mos .
if you see the datasheets, the Rds ON for these devices is high.
Later i found a cheaper source for SOT23 in my country and with milli ohms of RDS on. they have 1 amp capacity to delver. Now as my board (s) is already made, i managed to mount them on solder side and things went well.
a long story, perhaps repeated thoughts
all the best
1. if the smd op amp is planned you can use6420, otherwise with dip8 versions, we used either MCP6271, MCP6281 or MCP601
2. If yi suggest better use NDS356 as its ON resistance is very low and current capacity is more than 1amp
if you have original IRLML6402 , of course you can use them.
3. For N mosfet, i preferred to use si2302 as it is good and we get then cheap at 12 or 13 nos per $.
4. the Vf of the schottky diodes is far less. Even the original design they used schottky types, but in SMD.
I will use MCP6271.
For P mosfet, (FDC6420C replacing) it is easier to find IRLML6402, so i decided to use it also for P mosfet.
For N mosfet, (FDC6420C replacing) I can find SI2302, but CDS version only. SI2302CDS Is it ok?
si2302CDS appears to be ok, higher current capability, provided it is not too costly.
in the absence of D4, any external voltage could reach out to usb on its pin1 (Vusb) getting path thro' internal diodes of the FET devices. D4, i suppose, prevents that.
si2302CDS appears to be ok, higher current capability, provided it is not too costly.
in the absence of D4, any external voltage could reach out to usb on its pin1 (Vusb) getting path thro' internal diodes of the FET devices. D4, i suppose, prevents that.
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