Stuff you wanted to know but were afraid to ask

Is there an accepted convention for numbering components in a circuit? Like does R1 start at the signal input? Do they go through the signal path and then to the power supply? How are they chosen?
 
Harry Klippton said:
Is there an accepted convention for numbering components in a circuit? Like does R1 start at the signal input? Do they go through the signal path and then to the power supply? How are they chosen?
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I usually just layout the schem then Ill let the program annotate the schematic. It'll start from the left side and sort of logically number them for you. You might have to go in to clean it up if you feel so but i found this is enough for me to understand it.
 
Harry Klippton said:
Is there an accepted convention for numbering components in a circuit? Like does R1 start at the signal input? Do they go through the signal path and then to the power supply? How are they chosen?
Click to expand...

In consumer electronics (televisions, VCRs, etc) with large circuits they were typically numbered by section. R1xxx - Power supply, R2xxx - vertical deflection, etc. Within each group they were usually ordered in sequence horizontally from left to right on the page, but not always. The BOM would also give the X/Y coordinates (based on the grid on the top/bottom of the sheet) to quickly locate a component on the schematic.

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These were much larger schematics than we deal with. Usually many sheets that unfolded like a road map. Each sheet was about the size of a theater poster when unfolded.
 
One of my friends took an electronics class in college and part of one of their labs was repairing a broken wideband radio. He said they were given a schematic to help check over the circuit and it unfolded into 7 or 8 big pages.
 
cdwillis said:
One of my friends took an electronics class in college and part of one of their labs was repairing a broken wideband radio. He said they were given a schematic to help check over the circuit and it unfolded into 7 or 8 big pages.
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Before I got into working on MRIs, I worked in x-ray. Before refurbished/salvaged/second had parts were a thing(early-mid 90s(, GE would send out schematics for everything with new systems. The X-ray system schems were several 6 inch 3 ring binders of fold outs.
You could fill half a basketball court trying to trace a 5v control signal.
 
I always scold the gods because one nut on a toggel switch makes it always higher than the pots and I have to bend the pins of the pots to make them longer. Do you attach the switches without any nut between switch and enclosure or do you scold and bend?

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If you intend to tighten the nut on the outside of the front panel, then you also need a nut on the inside because otherwise you can overstress the joint between the threaded bushing and switch body when you tighten the outside nut. On the other hand, if you don't need the switch to support the board (in most cases, you won't), then you can omit all of the nuts & washers from the switches. There are low-profile switches, but it takes some searching to find them.

I usually do what Robert described above. Bending the legs right at the phenolic plate as shown above is a good way to crack the pot.
 
Chuck D. Bones said:
If you intend to tighten the nut on the outside of the front panel, then you also need a nut on the inside because otherwise you can overstress the joint between the threaded bushing and switch body when you tighten the outside nut. On the other hand, if you don't need the switch to support the board (in most cases, you won't), then you can omit all of the nuts & washers from the switches. There are low-profile switches, but it takes some searching to find them.

I usually do what Robert described above. Bending the legs right at the phenolic plate as shown above is a good way to crack the pot.
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I believe overtigtning a switch where the internal nut threaded a touch closer to the switch body caused enough flex to be the root cause of a board failure I had a few months back.
 
Ok, I will leave the nuts on the switches on the inside. They crack easy yes but with patience there was only one casualty out of a lot of pots.
Temporarily mounting and soldering is the way to go but sometimes the nut won't sit flush on the switch body because there is a small nose (?) - I don't know the english term - on the thread which prevents the nut from sitting flush. Is this (a) a cheap switch (b) intended to turn the nut with full force on it like a kind of a self-locking nut? I can't remember in which pedal I one in but I will search for it. In this case the pins of the pots were not long enough to go through the pcb.
 
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