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etpm@whidbey.com: May 06 05:37PM -0700 I want to use a hobby BLDC motor to power a compact high speed spindle to be used for engraving and the like. Mainly because they are so compact for the power and speed. I cannot find, for a price I can justify, a 24,000 to 40,000 RPM spindle that will fit in the space I want to put it. Looking at some hobby BLDC motors and then buying some to experiment with leads me to think that one of these motors may work. I have looked online for answers about these motors and maybe I'm just dense (good possibility) but I haven't been able to find exact answers. Maybe someone here can help. Motors are rated RPM/volt. This means maximum RPM per volt of course. If the motor is supplied with a higher voltage from a supply that limits the current to stay below the specs of the motor will higher RPM be possible? The ESCs (Electronic Speed Controller) are voltage and current rated. Could the output an ESC rated for a lower voltage and current be used to drive control power transistors in order to get around the lower voltage and/or current rating if a sensored motor is being used? I don't need to use a hobby ESC but they are plentiful and cheap. And all assembled. Which is most important. But I would be fine using some other BLDC motor driver in order to get the desired RPM that I want. I can do all the precision machining necessary to make the spindle that will hold the carbide cutting tools and to interface the motor with the spindle. I do not yet know enough about balancing in order to dynamically balance a motor which causes too much vibration from an out of balance condition but I think I can learn enough to do it. I am good with mechanical systems and have a pretty good intuitive feel for them. It's the electronics I'm not so good at. Thanks, Eric

"pfjw@aol.com" <peterwieck33@gmail.com>: May 07 04:28AM -0700 If you (spendy) source a servo-rated BLDC motor, it will tolerate all sorts of abuse, and may be loaded to a dead-stop without damage. And, if you are going to be doing this - purchase the correct speed control rated for the full shorted load of the motor. As there are no brushes, that is not the same as a short-circuit as it would be in a brush-type DC motor.   Peter Wieck Melrose Park, PA

bobrweber@gmail.com: May 07 06:29AM -0700 I have played around with these motors making drones from scratch. You can't just buy a motor and ESC connect them together and have it run. The input to the ECS is a pulse that varies in width for the desired speed of the motor. the direction of spin is controlled by how the 3 wires to the motor are connected (reverse any 2 and the motor spins in the opposite diredtion). I have run these motors without the cpu controller that makes a drone fly but you need 2 things. A wireless control transmitter that usually has joy sticks to control the speed and direction of the drone (Usually $50 on up). A receiver that can be directly connected to the input side of the ESC to supply the appropriate pulse to the ESC (about $15). The ESC supplies the 5v back to the receiver so no extra power supply is needed other that the high current one used to power the ESC itself.   There are probably controllers that can be used with these BL motors directly but I have not researched these. Since the price of a wireless controller/receiver pair is so low I doubt that a dedicated controller would be worth the cost. If you were an electronics hobbyist you could build a controller that would supply the correct pulse to the ESC.   Hope this helps.   ...bob

"pfjw@aol.com" <peterwieck33@gmail.com>: May 07 06:51AM -0700 One more thing - an unbalanced motor spinning at 24,000 + rpm will destroy itself in short order. I suspect that the motor itself will be the least of your worries.   At the same time, is this engraving device for a pantograph, or similar, such that an off-the-shelf engraver would not be suitable? There are some pretty good ones out there.   https://www.gesswein.com/p-2557-foredom-power-graver.aspx?gclid=CjwKCAjw8r_XBRBkEiwAjWGLlESlB2zvwLG2Covx4zMNmIheomOHFURpCrIzKeQWP7pGlPkjFtI3GxoCs5QQAvD_BwE   That for the price will probably be competitive with your home-brew at the end of the process.   Peter Wieck Melrose Park, PA

Jeff Liebermann <jeffl@cruzio.com>: May 07 08:01AM -0700 >There are probably controllers that can be used with these BL >motors directly but I have not researched these.   Ebay shows 700 listings for such controllers: <https://www.ebay.com/sch/i.html?_nkw=brushless+motor+speed+controller> Most are for eBike and electric scooter speed controls but the smaller boards might be usable.   -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558

bruce2bowser@gmail.com: May 07 12:41AM -0700 > There is a quality auction on Friday afternoon. > Fireworks, as usual.   > We all look forward to seeing you there!   Will every table and stand have a microscope :?

"pfjw@aol.com" <peterwieck33@gmail.com>: May 07 04:20AM -0700 > Will every table and stand have a microscope :?     There will be at least one - for checking styli - but on occasion some show up for sale.   Peter Wieck Melrose Park, PA

"pfjw@aol.com" <peterwieck33@gmail.com>: May 06 01:15PM -0700 On Sunday, May 6, 2018 at 12:32:50 PM UTC-4, Tom Del Rosso wrote:   > Are those designed to work in series with a ballast?   Some do, some come with a bypass that fits into the starter socket. Depends on which you choose. I prefer the latter as the system is more simple in place. But that option costs a buck or two more.   Peter Wieck Melrose Park, PA

"J.B. Wood" <arl_123234@hotmail.com>: May 07 06:41AM -0400 > Glowstarters are widely available, perform poorly but work. The glowswitch is far smaller than the plastic container. > A relay with brief time delay makes a much better starter.   Hello, and I have to take issue with your "perform poorly" remark. Glow switches (aka "starters") have been around for decades and are very reliable. And if they're reliable and work, how do they poorly perform?   In a traditional fluorescent lamp (hot cathode type) fixture with a coil ballast the lamp may pulse a few times before the gas discharge path is established. The ballast performs the functions of both a current limiter and providing a temporary voltage boost to establish the gas discharge path. When the glow switch disconnects after the lamp filaments have been heated there may not be enough of a voltage boost to fire up the lamp because of when this occurs on the AC cycle. Usually no more than a couple of start repeats are required and that's why the lamp pulses. In any event glow switches are quite reliable and cheap to replace when required. Sincerely,     -- J. B. Wood e-mail: arl_123234@hotmail.com

Mike S <mscir@yahoo.com>: Apr 30 12:05AM -0700 On 4/29/2018 11:41 PM, Ivan Vegvary wrote:   > Need to replace a "button style" (Motorola MR2506) rectifier with a "stud mounted" one (Motorola 1N1190A) The stud mounted on has a higher rating. > Question: Data sheet says button battery cathode marked by "dot". Dot no longer visible on installed parts. Is it safe to assume that the wires from the transformer secondary lead to the Anode and the body of the "button style" (cathode) is pressed into the aluminum plate? > Thank you for your help.   Do you know the make and model of the charger?

Mike S <mscir@yahoo.com>: Apr 29 11:12PM -0700 On 4/29/2018 3:50 PM, whit3rd wrote: > for a 4.2V battery input, which a power-wasting resistor can never > improve on. Alas, battery and LED options must be driven by the > choice of such a chip. $3 for 10! 10pcs AMC7135 350mA LED driver SOT-89 Thank you!

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