Search found 1611 matches

by dyarker
Thu Oct 21, 2021 3:12 am
Forum: General Discussion
Topic: LM358 differential voltage and amplifier circuit
Replies: 5
Views: 103

Re: LM358 differential voltage and amplifier circuit

V_IN_12 is 2.45V. By itself that would cause V_OUT_1 to go to +5V, so V_IN_22 would be 6.97V. Which would actually drive V_OUT_1 lower then 5V. Making V_IN_22 lower, but not but not enough to make V_IN_22 about 2.45V. Voltage drop by Sensor_Res is swamped out. No point looking at OA2 section till OA...
by dyarker
Wed Oct 20, 2021 9:40 pm
Forum: General Discussion
Topic: LM358 differential voltage and amplifier circuit
Replies: 5
Views: 103

Re: LM358 differential voltage and amplifier circuit

What is the variation of LOAD you're trying to measure? And V_Out_Final for each end of variation?
by dyarker
Wed Oct 20, 2021 9:29 pm
Forum: General Discussion
Topic: LM358 differential voltage and amplifier circuit
Replies: 5
Views: 103

Re: LM358 differential voltage and amplifier circuit

What is the tolerance of resistors R1 to R4? The difference in resistance could cause the difference in voltage to OA1 to be larger than Sense_Res voltage. Try - Short Sense_Res, then adjust the R1, R2, R3, R4 so the voltage between V_IN_12 and V_IN_22 is zero. STOP! R4 is also feedback for OA1. I d...
by dyarker
Mon Oct 18, 2021 7:20 am
Forum: General Discussion
Topic: Starter Relay Trouble
Replies: 4
Views: 156

Re: Starter Relay Trouble

The link does not apply. It is for starting AC motors in refrigerators and air conditioners. No issues plugging everything back in. That would not seem to be the case. Does fuel pump run with temporary wire from battery? (disconnect the normal hot wire first) Same experiment with starter motor? (neu...
by dyarker
Sun Sep 19, 2021 2:56 am
Forum: General Discussion
Topic: MCP2551 Circuit Problem in automotive
Replies: 3
Views: 481

Re: MCP2551 Circuit Problem in automotive

Also, how many transceivers on the buss? Is the buss a star or a daisy chain? A daisy chain with a termination on the ends will have less transmission line pulse collisions. And can't see how power supply section on schematic regulates and filters the +5V. Cheers, (from additional reading - do you h...
by dyarker
Sun Sep 19, 2021 2:41 am
Forum: General Discussion
Topic: MCP2551 Circuit Problem in automotive
Replies: 3
Views: 481

Re: MCP2551 Circuit Problem in automotive

The attached schematic way too small to read, and looks like only one controller with transceiver anyway. So, do the CANH and CANL only go directly to CANH and CANL of other transceivers? (no extra grounds?) Are CANH and CANL on twisted pairs or just a pair of individual wires? Is a CANH and CANL pa...
by dyarker
Tue Sep 07, 2021 5:09 am
Forum: General Discussion
Topic: 555 Timer problems in a circuit
Replies: 1
Views: 410

Re: 555 Timer problems in a circuit

??? pin 1 of the 555 is not an emitter, it is common supply pin, and should not be open. Do you mean when collector of the transistor is open there is 20mA through the emitter of the NPN transistor? When the output of 555 (pin 3) is high, the base-emitter of the transistor is forward biased, so ther...
by dyarker
Wed Aug 25, 2021 6:29 am
Forum: General Discussion
Topic: Can lithium batteries be recharged?
Replies: 8
Views: 6176

Re: Can lithium batteries be recharged?

Good idea!
An LM621 is not a CR2032.
CR2032 is not rechargeable.
LM621 is rechargeable, and should be a valid replacement. Careful with Electronic Goldmine, do you need 100 of them?

Cheers,
by dyarker
Mon Aug 23, 2021 10:45 am
Forum: General Discussion
Topic: Do i need to buy a ballast resistor ?
Replies: 6
Views: 715

Re: Do i need to buy a ballast resistor ?

A. 50 Ohm resistor will draw about 600mA. Wouldn't that plus LED still be less current than incandescent or quartz?

B. I wouldn't make the change myself. A car that comes with LED headlights won't need a resistor to "fool" the car computer.

Cheers,
by dyarker
Fri Aug 20, 2021 6:53 am
Forum: General Discussion
Topic: Do i need to buy a ballast resistor ?
Replies: 6
Views: 715

Re: Do i need to buy a ballast resistor ?

An alternate reason for resistor - From google.com Headlight LED load resistors prevent "bulb out" error messages and bulb flickering . These 6 ohm 50-watt load resistors compensate for the low power draw of 9005 LED bulbs so that they can communicate properly with your vehicle's computer system. If...
by dyarker
Thu Aug 19, 2021 12:05 pm
Forum: General Discussion
Topic: Do i need to buy a ballast resistor ?
Replies: 6
Views: 715

Re: Do i need to buy a ballast resistor ?

Info like did you replace a nonLED type headlight with an LED headlight?

The purpose of resistor in series with LEDs is to limit current. Of coarse current through a resistor will cause a voltage across the resistor.

Cheers,
by dyarker
Fri Aug 13, 2021 4:55 am
Forum: General Discussion
Topic: Can lithium batteries be recharged?
Replies: 8
Views: 6176

Re: Can lithium batteries be recharged?

BOOM!!!!
Unless package they came in says rechargeable.
by dyarker
Wed Aug 11, 2021 11:15 pm
Forum: Computer Programming
Topic: Shift Register IC's 74HC164, 74HC165 And 74HC595
Replies: 3
Views: 1859

Re: Shift Register IC's 74HC164, 74HC165 And 74HC595

TTL refers to voltage levels and impedance of the serial stream. (about 0 and almost +5V)
As opposed to an RS-232 (upto +25V downto -25V)serial, or current loop (+20mA / -20mA) serial.

Cheers,
by dyarker
Mon Aug 09, 2021 1:35 am
Forum: Computer Programming
Topic: What happen to programing for bme280?
Replies: 2
Views: 1899

Re: What happen to programing for bme280?

You mean the temperature/humidity/air pressure sensor? Had to look up the part number. Maybe most others haven't heard of it either. If not that sensor, then really, really, don't know what it is. Sorry! (added - if is sensor then standard I2C or SPI interface. the only programming is dependent on w...
by dyarker
Sun Jul 18, 2021 11:31 pm
Forum: Computer Programming
Topic: PIC Assembler 16F872 I2C Overview
Replies: 4
Views: 2152

Re: PIC Assembler 16F872 I2C Overview

Link is to a more general microcontroller.

The follow questions are too big to get into.