For those interested in the NPN transistor from the perspective of making a DIY sensor, I would suggest that the key aspects are low noise - Hfe can be quite low (about 70 - so pick a part with a range of about 70-150ish) but it does need to perform well at low Vce. The freqency is only 220Hz so focus more on DC perfromance and you can have very low frequency - the HP part is listed as 80MHz.
I thought I had added it already - how strange. anyway added to the description now butit is Github link github.com/pshersby/HP-Cal. I have checked and it is set to public access. I also took a quick look at the readme and the version on github does include the modifications that I talked about in the videos - board error is fixed, the switched moved further apart, holes etc. Gerbers, drill holes etc are in the Defualt Configuration/outputs folder
@@40dobbie Altium CircuitStudio. Not sure they would load into the community CircuitMaker but I think Altium do a free viewer and you might be able to import into some other freeware pcb software (or download an evaluation copy of either circuitstudio or designer. But the gerbers should be fine for most manufacturers
I do have a couple spare but they are the version with the fault that I had to add a mod wire for. You would be better ordering the corrected version direct from JLCPCB that is available on github - see my other reply. You say you want to build a sensor - Not sure the Calibrator PCB would help too much if you plan to build a DIY sensor, sure the small bit in the middle is the same and the pinout is right but there are some slight differences in the way the signal inputs from the diode/thermocouple on a sensor and the way the voltage divider in the calibrator works, mainly relating to the differences in impedence. The service manuals that I linked across the series have several sensor schematics. In terms of sensor the challenge is that the actual sensing component has to be logrithmic (power in dB in to linear voltage out) so a diode sensor for example has to work at very low voltage/current and have an extended non-linear region, the signal level is tiny so noise is a problem, and finally you need to maintain 50 ohm input impedence across a wide bandwidth.
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For those interested in the NPN transistor from the perspective of making a DIY sensor, I would suggest that the key aspects are low noise - Hfe can be quite low (about 70 - so pick a part with a range of about 70-150ish) but it does need to perform well at low Vce. The freqency is only 220Hz so focus more on DC perfromance and you can have very low frequency - the HP part is listed as 80MHz.
Hello I like to make one DIY sensor but then get the PCB, some possibility to get the PCB? I'm locate on UK
hello Peter, would it be possible to add the link to your Github location? I tried to find it, but was unsuccessful. regards, rob
I thought I had added it already - how strange. anyway added to the description now butit is Github link github.com/pshersby/HP-Cal. I have checked and it is set to public access. I also took a quick look at the readme and the version on github does include the modifications that I talked about in the videos - board error is fixed, the switched moved further apart, holes etc. Gerbers, drill holes etc are in the Defualt Configuration/outputs folder
@@MakeOrRepair Ah, thanks! in what pcb software did you design the schematics and PCB?
@@40dobbie Altium CircuitStudio. Not sure they would load into the community CircuitMaker but I think Altium do a free viewer and you might be able to import into some other freeware pcb software (or download an evaluation copy of either circuitstudio or designer. But the gerbers should be fine for most manufacturers
I like to make one DIY sensor but then get the PCB, some possibility to get the PCB? I'm locate on UK
I do have a couple spare but they are the version with the fault that I had to add a mod wire for. You would be better ordering the corrected version direct from JLCPCB that is available on github - see my other reply.
You say you want to build a sensor - Not sure the Calibrator PCB would help too much if you plan to build a DIY sensor, sure the small bit in the middle is the same and the pinout is right but there are some slight differences in the way the signal inputs from the diode/thermocouple on a sensor and the way the voltage divider in the calibrator works, mainly relating to the differences in impedence. The service manuals that I linked across the series have several sensor schematics. In terms of sensor the challenge is that the actual sensing component has to be logrithmic (power in dB in to linear voltage out) so a diode sensor for example has to work at very low voltage/current and have an extended non-linear region, the signal level is tiny so noise is a problem, and finally you need to maintain 50 ohm input impedence across a wide bandwidth.