So I designed a new product, specifically a thermostatically regulated PWM fan controller for motorcycles that either already have or have been converted to an electric fan.
I own a Honda CX500 Custom, often referred to as a SilverWing and there are still a ton of them in use due to their longevity. (long story) Most of them came with a manual fan connected to the end of the camshaft but 30+ year old plastic fans have a habit of coming apart and taking the radiator with them. The only replacements are usually also already old so a lot of people are converting by taking off the plastic fan and mounting a small electric in there controlled by a simple thermostatic switch glued to the top of the radiator.
That works, but it wasn't accurate as there's always going to be hot water hitting the top of the radiator and if you're traveling at any speed it doesn't really need a fan to bring the coolant back down to temperature. The solution? An LM35 temp sensor IC in the TO-220 package at the bottom of the radiator right near the return hose feeding a PWM control circuit that has some adjustments as to when and how fast it runs depending on the temp that's sensed. I'll eventually post the circuit when I get the BOM and PC board layout pix & files completed.
The problem? The ideal IC I designed it around is old but I had to keep the design as through-hole so people could buy just the PC board or a kit of parts from me if they wanted to assemble it themselves. Just in the one little forum on my particular bike interest has already spiked like crazy and now that I'm starting to get the BOM together I'm finding that the IC is almost non-existant in supply. I got all but two that Mouser had, DigiKey said they had 128 last night, this morning they said they only had 100 but when I finally got a PO together it turned out they found the other 128 so I've now cornered the market and will have 278 of them in stock. Microchip Direct (with whom I've got an account) only has 24 left but are scheduling a production run in February if you get your requirements in early. Farnell has 50, but that's across the ocean from me. I haven't a clue how demand is going to go once word starts to get around the other motorcycle forums, it'll even work for cars or anything else water cooled for that matter and it's possible this may be as big of a hit as that guy who designed all those signs everyone helped with not long ago.
Anyhow, facing a potential demand that would be kinked by shortage of the IC I've about talked Mouser into putting in an order with Microchip so that at least someone will have them in stock. In the meantime I'll be glad to sell a few of what I've got if anyone wants to build one of these things once I release the rest of the files.
What the heck, here's a schematic of the prototype as it sits but I don't have any values listed on it yet. I will tell you that the IC is:
http://ww1.microchip.com/downloads/en/DeviceDoc/21756b.pdf
and the temp sensor is a simple LM35 in the TO-220 case.
Pretty much a raw schematic but you can get an idea by looking at it:
http://www.innoengr.com/images/fan_controller.jpg
When this is all done I think I'm going to submit it to the forum as a full project.
I own a Honda CX500 Custom, often referred to as a SilverWing and there are still a ton of them in use due to their longevity. (long story) Most of them came with a manual fan connected to the end of the camshaft but 30+ year old plastic fans have a habit of coming apart and taking the radiator with them. The only replacements are usually also already old so a lot of people are converting by taking off the plastic fan and mounting a small electric in there controlled by a simple thermostatic switch glued to the top of the radiator.
That works, but it wasn't accurate as there's always going to be hot water hitting the top of the radiator and if you're traveling at any speed it doesn't really need a fan to bring the coolant back down to temperature. The solution? An LM35 temp sensor IC in the TO-220 package at the bottom of the radiator right near the return hose feeding a PWM control circuit that has some adjustments as to when and how fast it runs depending on the temp that's sensed. I'll eventually post the circuit when I get the BOM and PC board layout pix & files completed.
The problem? The ideal IC I designed it around is old but I had to keep the design as through-hole so people could buy just the PC board or a kit of parts from me if they wanted to assemble it themselves. Just in the one little forum on my particular bike interest has already spiked like crazy and now that I'm starting to get the BOM together I'm finding that the IC is almost non-existant in supply. I got all but two that Mouser had, DigiKey said they had 128 last night, this morning they said they only had 100 but when I finally got a PO together it turned out they found the other 128 so I've now cornered the market and will have 278 of them in stock. Microchip Direct (with whom I've got an account) only has 24 left but are scheduling a production run in February if you get your requirements in early. Farnell has 50, but that's across the ocean from me. I haven't a clue how demand is going to go once word starts to get around the other motorcycle forums, it'll even work for cars or anything else water cooled for that matter and it's possible this may be as big of a hit as that guy who designed all those signs everyone helped with not long ago.
Anyhow, facing a potential demand that would be kinked by shortage of the IC I've about talked Mouser into putting in an order with Microchip so that at least someone will have them in stock. In the meantime I'll be glad to sell a few of what I've got if anyone wants to build one of these things once I release the rest of the files.
What the heck, here's a schematic of the prototype as it sits but I don't have any values listed on it yet. I will tell you that the IC is:
http://ww1.microchip.com/downloads/en/DeviceDoc/21756b.pdf
and the temp sensor is a simple LM35 in the TO-220 case.
Pretty much a raw schematic but you can get an idea by looking at it:
http://www.innoengr.com/images/fan_controller.jpg
When this is all done I think I'm going to submit it to the forum as a full project.