I would like to control the speed of a 3/4 HP 12 VDC motor with a 3.3 VDC microcontroller. I've seen in past issues where PWM was used to control small DC motors but not fractional HP motors.
Can someone show a circuit to interface the high power motor with a low power MCU from a 12V auto battery? Presently, I'm trying to use a Freescale MC9S08QG8 MCU. Ultimately, I would like to use the motor as a brake, and then reverse rotation on a small flywheel for a few revolutions.
The motor goes the same direction all the time, just the flywheel will reverse direction.
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I’m trying to repair a microprocessor controlled massage chair, imported by HWE, Inc., Los Angeles. ID S-KMS mfg # 000101, additional number 61011-L.
NEC is the processor manufacturer and has indicated in thier product description that the processor is a uPD75004CU four-bit discontinued part. I am reasonably sure there is an onboard program, but do not know enough about it to get it into test mode.
It appears to be completely shut down. I have scoped the in and out, but there is no activity.
If the processor is dead, then a $1,500 item is junk, unless someone can help.
I would like to have a schematic, service manual, literature, or advice.
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I'm attempting to repair a PC board for a RadioShack PT Cruiser remote control car. The IC (20-pin) has the following numbers printed on the top: S111g, KJET IC001, OU97112.
In the tech manual, the IC is identified as KS57C0301.
(1) Program memory is 1K byte (KS57C0301) and 2K byte (KS57C0302).
(2) Data memory is 128x4 bit (KS57C0301) and 256x4 bit (KS57C0302).
Parts from RadioShack are no longer available. Any help in identifying a substitute would be appreciated.
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I want to design an inexpensive audio graphic equalizer that us older guys (and ladies) can use with our radio (ham) gear. What I envision is a programmable equalizer that can be programmed to boost frequencies based on hearing tests. Even better would be a stereo equalizer that can be used with a stereo headset to allow us old timers to hear better.
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Currently I am using two thermostats to activate an attic fan: one thermostat to determine a cool outside temperature and a second thermostat to determine the attic temperature. When the differential between the two reaches the set point of the two, they both turn on the attic fan, pulling cooler outside air up and through the attic. This only works when each thermostat reaches their "set" point temperatures. I would really like to be able to have the fan come on when a variable differential temperature — say 20 degrees — is reached, regardless of outside or attic temperatures; also, only if the attic temperature is warmer than the outside temperature.
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I'm looking for a schematic solution to wirelessly indicate the water level of a distant water tank more than 100 m away.
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I am looking for some technical information for repairing various fusion splicers on the market such as Fitel, Sumitomo, and Fujikura. Anybody have any information they are willing to share?
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I have some industrial equipment inherited from a deceased customer. Two transformers, vintage WWII, 10 and 5 KVa and one transformer probably, 15 KVa with SCRs but no control board. This equipment was originally intended for wire heat treat service, 28 VAC secondaries. I have had them 20 years or more. I’ve been trying to cook up a stable circuit for firing SCRs for all the transformers. I have worked with such circuits all my professional life but [now 76 yrs] stability is eluding me. Industrial electrical service is always noisy and welding especially so. I know I need zero crossing sync and I need 0.008 sec to zero sec adjustability for the triggers. It must also be jitter free. This is just a hobby because nobody buys antique transformers except for scrap, which might be my best business decision considering the times. I do have the transformers and the SCRs. My heirs can scrap the units out after my reward. I have lots of scrapables to play with and nothing else but time.
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How does one replace a spider IC?
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I would like to know how to build a self-powered currect switch to monitor a lamp pole light. I need it to output an open or closed contact, so I can sense if there is current or not.
The light pole voltage is 120V at a range of 1A-10A. Anything above 200-500 ma current is on or closed contact. Otherwise, no current, open contact. I need it as small as possible and over-voltage and over-current protected.
Any help out there?
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