# How can I identify these capacitor values?

I’m trying to build the power supply from this schematic. I’ve been purchasing the parts, but am confused about the capacitors I’ve labeled, especially became their numbers start with “R”. What are their values? What common sense can I use so I can continue to find this out myself?

• Taking a wild guess: I have seen a few cases where resistances were written a for example 1R1 to represent a 1.1 ohm resistor. So, those might be 0.1 and 0.01 microfarad capacitors – JRE Oct 28 '18 at 20:30
• I agree with ^^. Also look at the circuit, what is does and what would be appropriate: C4 0.01uF = 10 nF, C2, C5: 100 nF seem appropriate for supply decoupling around a 78L05 regulator. Then C10 is R1 so also 100nF, it's in parallel with a 220uF electrolytic so just providing some HF decoupling, 100 nF also seems appropriate. – Bimpelrekkie Oct 28 '18 at 20:38
• How are you going to go about the diode D2, which is marked "Hi-Fi special" ? – Nick Alexeev Oct 28 '18 at 21:41
• Wow, those are some ancient transistors. – Sparky256 Oct 28 '18 at 22:06
• @Nick Alexeev I think that's literally a normal diode, and its purpose is just being explained on the schematic. When I look at the whole schematic, all diodes (that aren't zener or schottky) are marked that way. – ToastHouse Oct 29 '18 at 1:35

Since a couple of other commenters seem to think it reasonable, I'll go ahead and make an answer from my comment:

Taking a wild guess:

I have seen a few cases where resistances were written as for example 1R1 to represent a 1.1 ohm resistor.

So, those might be 0.1 and 0.01 microfarad capacitors.

Additionally, those values would make sense in the given positions for a 7805 linear voltage regulator.

• This would be my interpretation as well. The use of R is usually exclusive to resistors, but this is the only reasonable interpretation of this numbering scheme. The 'base unit' for capacitors is either microfarad or picofarad, but since a 0.01 picofarad capacitor wouldn't make much sense, 0.01 μF is more likely. – Hearth Oct 28 '18 at 21:12
• I answered a question just like this a few months ago. Treat the 'R' as a decimal point. A real decimal point may not print good or large enough to see. More and more often I see nF being used instead of fractional uF values. – Sparky256 Oct 28 '18 at 22:04
• Another name for 'decimal point' is 'radix point'; you see that 'r' in places that have nothing to do with electronics. (I use it when I'm writing fractional binary numbers, for instance: 1011r1001 gets less argument from the audience for some reason than 1011.1001). – TimWescott Oct 28 '18 at 23:54