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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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23rd Jun 2004, 7:52 pm | #1 |
Dekatron
Join Date: Oct 2003
Location: Southport Lancashire, UK.
Posts: 3,221
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Buying Resistors
I am not sure whether this is the right place for this enquiry, but here goes!
I am quite new to radio repairing and have only done a few. One of my problems is the bewildering values of components, particularly resistors, used. Capacitors aren't so bad as the values seem fairly standard and I have built up a reasonable selection by buying more than I need and by assuming that most will need replacing anyway to make the set really reliable. Resistors seem much more reliable and so I haven't built up a stock. I see mixed lots on Ebay which might be a good start, but am not sure what wattage I need. Is this a good source or does anyone know of another source of "mixed bags"? Also what wattage should I use for general circuit work (as opposed to mains smoothing and such)? Thanks Paul Last edited by Chris_C; 28th Dec 2004 at 2:12 pm. |
23rd Jun 2004, 8:03 pm | #2 |
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Location: Cardiff
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Re: Buying Resistors
The original resistors would have been 1/4W or 1/2W. However modern parts of these ratings will be too small, so we normally use 1W resistors as replacements. 5% tolerance is plenty good enough. The beige coloured ones don't look to out of place.
As for values - yes you will need a larger range, but you certainly don't need all of them. There generally aren't that many lower value resistoirs in radios, and where there are they tend to be more reliable. My suggestions for starters would be: 10K, 22K, 47K, 100K, 150K, 220K, 330K, 470K, 680K, 1M, 1.5M, 2.2M, 3.3M, 4.7M, 6.8M and 10M. Get about 10 or 20 of each - they are cheap enough! Mixed bags may contain more of the lower values that you are less likely to use. The trouble is that you don't know. You also have to sort them all out, which can be tedious and time-consuming - especially if you have to read and work out the colour code (with experience you just look at a resistor colour code and know the value instanty). |
24th Jun 2004, 10:08 am | #3 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
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Re: Buying Resistors
I would also suggest some lower values like 100 ohms
220 ohms and 470 ohms of about 1 watt rating to replace cathode resistors in output stages. Rich.
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12th Dec 2004, 4:51 pm | #4 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
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Re: Buying Resistors
Hi Gents, you can always series and parallel resistors to get the value that you do not have. This was often done in repair shops that had " run out " of a specific value, or needed a higher wattage than was available.
Ed Last edited by Darren-UK; 19th May 2007 at 11:52 pm. Reason: Brought in line with remaining posts. |