Where can I get the smaller ones for cheap and what are the smaller resisters called?The small resistors get hotter and could be made of more temperature stable metal so they can stay within range at higher temperature.
If the lead is bigger diameter it uses the PCB as heatsink.
Cool! Thank you very much!Resistors come in many sizes depending on manufacturer. You can get them cheap on ebay. Most ebay dealers specify the wattage only, you could be able to email them and ask for the dimensions. Check the price of RS or Farnell (I assume you have them in NZ) they give the size.
I got some 1/2 watt resistors from a shop called jaycars here in New Zealand and then I wanted to get a lot more and since I'm a cheep student I didn't want to spent a whole lot of money at jaycars I jumped on eBay to get more 1/2 watts for cheaper as I'm sure plenty of people do but when I received them today I found that they were 2x bigger then the ones from jaycar so I checked the packaging on both the jaycar resistors and the eBay ones and tho only difference that I could find was that the jaycar ones were labelled 0.5w and the eBay ones were 1/2w... Correct me if I'm wrong but 0.5 and 1/2 is the same thing right? So why are the eBay resistors bigger? I'll post an image of them side by side too show you what I mean.
I'm home and I've taken a photo of the 1/4 watt, "Supposed" 1/2 watt and the bigger 1/2 watt and I've taken a photo next to a ruler and it seems that the 1/4 and the small 1/4 are the same size but I did find the pack that the small 1/2 watt were in and it said it was "mini" could that be the reason it's so small?View attachment 96384
Oh wow thank you! I'm about as new to this as you can get so any info/resources that will teach me how to create guitar pedals as well as be able to tweak there sound will be more then appreciated!Hy,
Now that you have indicated the resistor size I can assure you that smaller resistors are 125mW and the bigger resistors are 250mW; neither are half watt.
The reason why the issue even arose is because of the vendor’s loose and unqualified description. The only way to establish what a part can do is to get the exact part number and check the datasheet. The trouble is that many second line retailers sell unbranded and unspecified components. Their description are also loose to say the least. The rule is never buy anything until you have established it’s specification- vendors descriptions are riddled with errors anyway (not so the mainline vendors like RS, Farnell, Mouser etc, but, even they make the odd mistake). To make matters worse there are even errors on data sheets, but rarely.
The other thing is that the rating of any component depends on the conditions. For example, the rating of a resistor may be 1W, but that may be at a body temperature of 25 deg C. In practical terms, unless the resistor were immersed in a bath of oil at around 10 deg C, this is a meaningless specification. What you need is the resistor dissipation in free air at 25 deg C.
But, if the resistor is mounted in your equipment and the air in the equipment is 50 deg C, a fairly normal temperature, then a 250mW resistor may become a 125mW resistor. The controlling factor, with all electronic components, is the maximum temperature of the active part: in the case of a resistor, the ceramic insulating tube (body) and the spiral film (resistor) deposited on it. With a transistor the active part is the semiconductor junction, which typically must not exceed 170 deg C or the transistor will be destroyed or permanently damaged.
As has already been said, there are a number of different resistor types: some information here: https://www.electro-tech-online.com/threads/transistor-equivalent.146091/page-27 Post 530.
I’m not sure how much you know about electronics; just in case, here is a bit of useful basic theory about resistor power dissipation:
(1) The power dissipated is a resistor is: the current flowing through the resistor squared, multiplied by the resistor value. So for example, if you had a 10 Ohm resistor with 2 Amps flowing through it, the power dissipation in the resistor would be (2 * 2) * 10= 40W
(2) The power dissipated is a resistor is also: voltage across the resistor squared divided by the resistor value. So for the same example, if you had a 10 Ohm resistor with 20V across it, the power dissipation in the resistor would be (20 * 20) / 10= 40W
(3) The power dissipated in a resistor is also: current flowing through a resistor times the voltage across the resistor. So again for the same example, the current flowing through the resistor would be 2A and thus the voltage across the resistor would be 20 Volts. Thus 2 * 20 = 40 Watts again.
There is a simple way to check if a resistor is OK as far as power dissipation goes: put your finger on it- if you can’t quite keep it there that is around 70 deg C and is a good design maximum surface temperature; anything higher is unwise. This is not the case for certain power resistors which can run at around 100 deg C.
After all that, I bet you wished you had never asked. I will get my coat now.
PS: you can check for yourself what wattage ratings your resistors are by using the formlae above and the finger test!
Oh wow thank you! I'm about as new to this as you can get so any info/resources that will teach me how to create guitar pedals as well as be able to tweak there sound will be more then appreciated!
Although everything spec explained is good, they "could" both be 1/2w with examples of both sizes in my link above.There are other characteristics which can affect vendor choice of body size such as Vmax, flame proof coating
They do come in different sizes. What voltage rating do you need? 250? 300? 500? 1600?
https://www.digikey.com/product-search/en?pv3=1&FV=fff40001,fff80482,40139&k=.5w+resistor&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25
A homogeneous film of metal alloy is deposited on a high grade ceramic body. After a helical groove has been cut in the resistive layer, tinned connecting leads of electrolytic copper are welded to the end-caps.
... they "could" both be 1/2w with examples of both sizes in my link above.
Awesome!! Can you suggest somewhere to start please? I have no clue! I'm currently saving up to get a few more bits of equipment one of them being a laser printer because it seems that's ink jet printers can't be used to print PCB layouts as far as I can tell.My pleasure Justin,
You are @ the right place. I have two axes and have had some amps, but only a practice combo now. Have designed and built many weird things. Long-term project is a guitar pickup: individual low turn coils for each string and built in opamps for each of the six channels- automatic hum bucking without loss of hi frequencies. Another long-term project is electronically controlled tuning and tremolo bridge. I had better stop now.. again
I honestly thought you were just going to point me in the direction of a good book but this is far more practical and much easier to get my self going. I'm going to save it to a word document in case someone else I meet down the road could use it.Hy Justin,
I just woke up.
Sure can advise how to start- it is a common question. Advise you hold the purchase of the laser printer for now.
I will put together a list of how to start designing and building electronic equipment. It need't be expensive.
A rough list (I will tidy up/fill in) of items needed to get into most fields: linear, digital, power. As I undrstand it, you are focusing on electonic music associated circuits, so not all the list will apply to you:
(1) Essential
(1.1) electronics reference book/epub
(1.2) soldering iron suitable for fine work
(1.3) precision wire cutterrs- I will recommend- not cheap, but not overly expensive
(1.4) precision fine nose pliers- as for wire cutters
(1.5) multimeter with good ranges- not expensive but must get the right one
(1.6) power supply- to be defined. but not expensive
(1.7) resistor set- type and ranges to be defined- you have some already
(1.8a) capacitors solid: 100nF ceramic
(1.8b) capacitors solid polyester (pollycarb much better but expensive): 1nf, 10nF, 100nF (1uF luxury item)
(1.9) capacitors electrolytic low ripple: 10uF, 47uF, 100uF, 470uF, 1,000uF
(1.10) capacitor elytrolytic high ripple (for PSU etc) 4,700uF
(1.11) BJT small signal: NBJT=, PBJT=
(1.12) BJT low power: NBJT=, PBJT=
(1.13) BJT high power: NBJT=, PBJT=
(1.14) FET: NFET= PFET=
(1.15) MOSFET medium powe: NMOSFET=, PMOSFET =
(1.16) MOSFET high powewr: NMOSFET=, PMOSFET =
(1.15) opamp jellybean:
(1.16) opamp high performance:
(1.17) opamp audio:
(1.18) variable resistor log: 10K log
(1.19) variable resistor lin: 100R, 1K, 10K, 100K, 1M
(1.20) strip board
(1.21) wire
(1.22) diode small signal: 1N4148
(1.23) diode medium current: 1N400x (400V)
(1.24) diode zenner low power: 3V3, 4V7, 5V6.
(1.25) voltage regulator: VREG+ = LM317, VREG- = LM337
(1.26) timer IC: LM555
(1.27) Soderwick (fluxed braid for removing solder)
(1.28) flux
(1.29) IC socket, turn pin:
(1.30) surface mount to DIL header board:
(2) Desireable
(2.1) Eye loup x20 magnification
(2.2) Workbench/table
(2.3) Small vice around 3.5 inch wide jaw
(2.4) screwdriver set
(2.5) small spanner set metric
(2.6) allen key set metric and imperial
(2.7) 1.5mm to 5mm bolts, nuts and washers
(2.8) junior hacksaw
(2.9) files: large, medium and keyhole
(2.10) twist drill set ( 1mm to 5mm)
(2.11) hand drill brace
(2.12) scalple
(3) Luxury
(3.1) ECAD software- EAGLE is free
(3.2) Simulation software- LTSPICE is free
(3.3) oscilloscope- not necessarily too expensive
(3.4) signal generator- not expensive
(3.4) plugs and sockets
(3.5) digital ICs
(4) Decadent
To be defined
Hi,
glad you found the long list of some use and not too daunting.
There are heaps of books around, but none I have seen yet hit the sweet spot of simplicity and practicality. With a bit of easy-t- learn basic theory, you can do your own designs, some pretty sophistoicated. Like everything in life, it is knowing the fundamentals that is enabling.
Just a silly example. When I started playing golf I could never get out of the sand in a bunker. I would swing away in clouds of sand and the ball just would just roll forward a few inches, so my swing count went up and up- I felt a right dick and my mates laughed their heads off.
But then we had a couple of lessons from a golf pro. He explained that you do not try to hit the ball with your club head as you would do on the freeway. No, instead, in sand, you hit down into the sand about an inch in front of the ball. I gave it a try- still a great cloud of sand but the ball popped up out of the bunker, no problem. Now, I have even holed from a bunker. If it hadn't been for that simple piece of advice I would still be thrashing away in the sand with no result. Now- I quite like bunker shots.
It was the same thing with writing. I used to stuggle like hell getting a report done until,l one day, an old hand in the technical publications department at work took my spaggeti proposal and turned it into silken text in about half an hour. Just like the bunker shot, I learned the techniques and now writing of any sort is no probs.
What I cannot get with though is the artistic side of life: dancing, singing, painting, playing a musical instrument (can't play my guitars), spelling- to me those are a complete mystery.
The list looks onerous but it is not. I have had an intro to electronics piece in my mind for years now. I plan to cover the whole thing, but in simple terms. The headings I have in mind are:
Safety
Theory
Designing
Documenting
Test Equipment
Electronic Components
Tools
Materials
Board layout
Mechnical (chassis, case etc)
Building
Testing
Faultfinding
Also what about playing the guitar/music are you finding hard? I might be able to help or at lest give you some info that might point you in the right direction.Hi,
glad you found the long list of some use and not too daunting.
There are heaps of books around, but none I have seen yet hit the sweet spot of simplicity and practicality. With a bit of easy-to- learn basic theory, you can do your own designs, some pretty sophistoicated. Like everything in life, it is knowing the fundamentals that is enabling.
Just a silly example. When I started playing golf I could never get out of the sand in a bunker. I would swing away in clouds of sand and the ball just would just roll forward a few inches, so my swing count went up and up- I felt a right dick and my mates laughed their heads off.
But then we had a couple of lessons from a golf pro. He explained that you do not try to hit the ball with your club head as you would do on the freeway. No, instead, in sand, you hit down into the sand about an inch in front of the ball. I gave it a try- still a great cloud of sand but the ball popped up out of the bunker, no problem. Now, I have even holed from a bunker. If it hadn't been for that simple piece of advice I would still be thrashing away in the sand with no result. Now- I quite like bunker shots.
It was the same thing with writing. I used to stuggle like hell getting a report done until, one day, an old hand in the technical publications department at work took my spaggeti proposal and turned it into silken text in about half an hour. Just like the bunker shot, I learned the techniques and now writing of any sort is no probs.
What I cannot get with though is the artistic side of life: dancing, singing, painting, playing a musical instrument (can't play my guitars), spelling- to me those are a complete mystery.
The list looks onerous but it is not. I have had an intro to electronics piece in my mind for years now. I plan to cover the whole thing, but in simple terms. The headings I have in mind are:
Safety
Theory
Designing
Documenting
Test Equipment
Electronic Components
Tools
Materials
Board layout
Mechnical (chassis, case etc)
Building
Testing
Faultfinding
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