Path: ...!weretis.net!feeder6.news.weretis.net!usenet.blueworldhosting.com!diablo1.usenet.blueworldhosting.com!feeder.usenetexpress.com!tr2.iad1.usenetexpress.com!69.80.99.26.MISMATCH!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Sat, 09 Mar 2024 23:14:44 +0000 From: John Larkin Newsgroups: sci.electronics.design Subject: Re: Motor Speed Control Date: Sat, 09 Mar 2024 15:13:20 -0800 Organization: Highland Tech Reply-To: xx@yy.com Message-ID: References: X-Newsreader: Forte Agent 3.1/32.783 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 66 X-Trace: sv3-tNfoDYeNJc0V7CdExKQvtCNy1sIq6Ed4Qs3xEnh+q+EiGQCA9esDPHCPQwauCgg/0fwjxy7Q39z1Ccn!LkkyWUN+pqwdU00C6k5Ujy/XOUwhleCd5ViEBaAp5usvbEDlEHhYMZWrHqP+TgayMvLDP+4KfjYm!J5a4bg== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 4238 On Sat, 9 Mar 2024 14:56:43 -0800, KevinJ93 wrote: >On 3/8/24 8:42 PM, Bill Sloman wrote: >> On 9/03/2024 5:49 am, KevinJ93 wrote: >>> On 3/7/24 8:48 PM, Bill Sloman wrote: >>>> On 8/03/2024 7:13 am, KevinJ93 wrote: >>> ... >>>>> >>>>> Not in 1970. Even after that time they did not possess any advantage >>>>> over DC motor drive with speed stabilization based on back-emf. >>>> >>>> Don't be silly. Back-emf depends on the strenght of the magnetic >>>> field generating the basck-emf, and that is temperature dependent. >>> >>> At about 0.2% per deg the magnetic field strength stability was >>> adequate for the speed accuracy required under the required >>> environmental conditions. >> >> Motors run hotter than their environment > >With only 50-100mW being consumed by the motor (10's of mA at 3-6V) the >temperature differential was small. > >>>> Synchronous motors rotate at a rate that reflects the stability of >>>> the frequency source that determines the drive frequency, and >>>> reasonably stable frequency source - watch crystals have been around >>>> for ages. >>> >>>>> Even for AC powered units where power was not an issue stepper >>>>> motors were never used. Synchronous motors with synthesized drive >>>>> were occasionally a feature but many/most used back-emf >>>>> stabilization with DC motors. >>>>> >>>>> ICs were available to integrate that circuitry: >>>>> >>>>> eg https://www.precisionmicrodrives.com/ab-026 >>>>> >>>>>>> Even implementing the discrete drive electronics would be more >>>>>>> costly than necessary at a time where individual transistors were >>>>>>> a significant cost; Philips' solution used two transistors - >>>>>>> creating a divide by 4 plus driver transistors plus an oscillator >>>>>>> would probably require about ten transistors plus numerous other >>>>>>> components. >>>>>> >>>>>> Which you could could buy in an integrated circuit. Most of mine >>>>>> were in a chunk of PROM. >>>>> >>>>> Not in 1970. Even by the late 70's a bipolar (P)ROM would use up all >>>>> your power budget. >>>> >>>> It didn't - and it wasn't bipolar. >>> >>> MOS EPROMS such as the 1702 were cumbersome to use with multiple >>> supplies required. >> >> It was one-time programmable, not an EPROM. > >If it was NMOS it was almost certainly an EPROM in a cheaper package >without the quartz window. 1702 was a p-mos UV-erase part. It was called an eprom.