hybridfree/eevblog-posts huggingface dataset:
I want to build a simple+cheap (small) antenna rotator.  - Page 1
Forum section: electronics / beginners

author: cdev
author_rank: Super Contributor
timestamp: July 01, 2020, 08:57:40 pm
content: I like to fool around with antenna designs, usually made on materials like cardboard or foam core with copper tape, but sometimes using other similarly light materials. They never would survive outside, so I use them indoors, mostly.I want to be able to put an antenna in my attic, hang them from a hook and spin them around a fulll 360 degrees without spending a lot of money.This is for indoors and I suspect a very small low capacity motor would do fine. I'm planning to put the motor above the antenna and hang it from above using some string or monofilament line . I want something slightly above the most basic rotator - I'd like to be able to know what angle the antenna was deployed at, and have a full 360 degree rotation ability.Anyway, does anybody know some good web resources on the basics of motion control, or has anybody built something like this?

author: Renate
author_rank: Super Contributor
timestamp: July 02, 2020, 09:21:05 pm
content: The old fashion cast aluminum housing rooftop antenna rotors used a two winding AC motor and a run cap.The two windings and the cap were in a triangle.Apply AC to one side of the cap, it turned in one direction, apply AC to the other side, the other direction.There was gearing and a contact that clicked about once a second that sent a pulse to the control unit to have a solenoid click the indicator to keep up.Simple, eh?Use a stepping motor in the attic and a smaller stepping motor at the control position wired in parallel.Have a little oscillator circuit with a center-off toggle switch to make it turn in either direction.Once this circuit is mechanically aligned, you won't have to worry about homing or power down.Of course, you could use a homing switch in the attic, a uP and a digital display.

author: cdev
author_rank: Super Contributor
timestamp: July 03, 2020, 02:08:20 am
content: Thank you, that sounds cheap and perfect.

author: bob91343
author_rank: Super Contributor
timestamp: July 03, 2020, 02:33:02 am
content: The better rotators use a pot to indicate position. Google CDR rotator and look at the diagram. There are various models but only two basic schemes.
Motor Current Decreasing Under Load??? - Page 1
Forum section: electronics / beginners

author: JayMan07
author_rank: Regular Contributor
timestamp: September 20, 2014, 12:32:57 am
content: I always assumed that electric motor current would increase under load, butevery time I test this motor I find that it decreases.It's a DC blower motor I have. It's 12V and draws 635 mA normally. If I put it under load (by blocking some the air flow) the current drops to about 450 mA.I tried to research this online, but everything I found said that current should increase under load. Am I missing something simple or what?

author: ignator
author_rank: Regular Contributor
timestamp: September 20, 2014, 12:51:33 am
content: Te blower is a 'pump'. By blocking the output, you reduced the power needed to move the air.So a decrease in input power is the correct observation. This is true for most pumps that are not positive displacement.I know it seems non-intuitive. The fan blades aerodynamically are in a stall, by blocking the air flow.

author: IanB
author_rank: Super Contributor
timestamp: September 20, 2014, 01:24:30 am
content: What ignator said. Blocking the air flow through a fan decreases the load on the motor. You can often tell this is happening from the way that the fan speeds up. Try it with a hairdryer (on cold): block up the inlet holes and the whine will increase as the blower runs faster.

author: JayMan07
author_rank: Regular Contributor
timestamp: September 20, 2014, 03:16:09 am
content: Ok thanks for clearing that up! That does make sense to me now. And I tried measuring the current on a regular DC motor I had laying around and found that it did rise a lot under load.

author: AlfBaz
author_rank: Super Contributor
timestamp: September 20, 2014, 03:29:59 am
content: Quote from: IanB on September 20, 2014, 01:24:30 amIt is a little counter intuitive but most of us would see this with a vacuum cleaner on a day to day basis.Years ago at a workshop we would start massive auxiliary fans after an overhaul with no load by blocking the intake

author: max_torque
author_rank: Super Contributor
timestamp: September 20, 2014, 01:13:10 pm
content: For fans / pumps etc Blocked airflow = less mass of air moved = less power required from motor driving fan.If you carefully use your finger (or better, a plastic biro or bit of wood) to "slow the fan down" by pressing it against the spinning fan hub, current should go up!

author: David Hess
author_rank: Super Contributor
timestamp: September 27, 2014, 12:47:48 pm
content: Quote from: ignator on September 20, 2014, 12:51:33 amThis is a great description of what is going on. I wish I had said it.
Motor Driver board Question - Page 1
Forum section: electronics / beginners

author: vargoal
author_rank: Regular Contributor
timestamp: August 08, 2015, 07:37:59 pm
content: I was working on fixing one of my two Dagu motor controller boards. I found this schematic (http://www.robotgear.com.au/cache/Files/Files/159_4ChannelDCMotorControllerSchematic.pdf). I figured out that what was broken on the board was the 74HC08 chips, I think I just plugged in a 12 V to VCC by accidentAnyway when I was looking at the schematic I was curious as to how the P-Channel Mosfet gate is set to 12V by a 5v logic circuit. I think it's because of the pull up resistors to the 12v battery but I don't see anywhere in the datasheet for the 74HC08 that says that it only pull's current. Would the 12v rail back drive the 74HC08, and if so does that damage it? Also forgive any faults in my statements as I am just beginning with electronics

author: SeanB
author_rank: Super Contributor
timestamp: August 08, 2015, 08:14:35 pm
content: 74HC03 is what is used, which is an open drain CMOS device. Thus it can be connected to a higher voltage than the supply, as indicated in the data sheet, though it is limited to 7V max.http://www.nxp.com/documents/data_sheet/74HC_HCT03.pdfThe IC might survive 12V applied to the output for a while, but some devices will not survive that. Running the motor at 12V will require something which is rated for 16V on the outputs.

author: vargoal
author_rank: Regular Contributor
timestamp: August 08, 2015, 08:51:59 pm
content: Thanks SeanB. Based on what you said I looked up more on CMOS and went back to the datasheet. It says "The input and output voltage ratings may be exceeded if the input and output current ratings are observed." It was in small print below the electrical characteristics section. I did the calculation and it does stay within that limit so it now makes sense that it works.
Motor driver current rating - Page 1
Forum section: electronics / beginners

author: init
author_rank: Contributor
timestamp: April 27, 2016, 05:40:43 am
content: I'm looking at putting a 12V DC motor with worm drive into a project I'm doing. It has a load current up to 7.5 A and a stall current of 31A. From a design perspective, I want to drive this motor with a H-bridge or two half bridge chips. Should I specify the chip current rating at the stall current or below? Do these chips usually have a stall current rating on top of operational current?

author: ataradov
author_rank: Super Contributor
timestamp: April 27, 2016, 05:58:41 am
content: Drivers typically specify continuous operational current and short-time overcurrent (typically for 10-100 ms).If there is a chance your motor will stall, you need to add stall detection and disable the driver in case if motor is stalled. Motors don't like to be stalled for too long.That's a very generic description. There can be other vital details, like start current, which will be higher than nominal operational current and you need to account for that as well.

author: init
author_rank: Contributor
timestamp: April 27, 2016, 06:29:47 am
content: Quote from: ataradov on April 27, 2016, 05:58:41 amMore specifically, I want a motor that can handle long static torque periods such as those used in a robot. Imagine holding a weight out perpendicular to your body and keeping it still, then shift it up above your head and hold it still - I want a motor that is suited to this kind of function. Assuming the amount of static torque required isn't huge (less than rated torque), does this mean the stall current will be less in any way?

author: ataradov
author_rank: Super Contributor
timestamp: April 27, 2016, 06:37:40 am
content: Quote from: init on April 27, 2016, 06:29:47 amThen DC motors is not what you want unless you want to deal with encoders and design a proper servo controller. It is not a trivial task.Quote from: init on April 27, 2016, 06:29:47 amI would go with stepper motors in this case. Way easier to control and their normal holding torque should be sufficient provided good mechanical design.
Motor driver won't talk to me :( - Page 1
Forum section: electronics / beginners

author: RippoZero
author_rank: Newbie
timestamp: April 18, 2024, 07:26:35 am
content: Got a pcb with a teensy 3.2 trying to talk to a motor driver(DRV8434s). I know information is transferred to the chip because I'm able to run a stepper motor, the signal from the micro also looks crisp. The problem is the DRV8434s SDO line, naturally it's connected to the standard MISO input for the micro. The signal is strange looking, it does not quite reach 3.3v and has a very slow rise time. It rests at about 0, opposite to the MOSI signal, resting at 3.3v. I found this puzzling.Among the things I've tried is lowering the frequency of the SPI bus, verifying values of supporting components, changing the IC, touching up solder joints and adding a pull-up resistor. Discovered I had connected the VSDO pin to the 3.3v rail though a resistor witch I swapped out for a wire.Don't hesitate to ask if you want more information

author: Psi
author_rank: Super Contributor
timestamp: April 18, 2024, 09:02:05 am
content: What voltage is on these pins of the DRV8434DVDDVCPVREFNFAULT

author: RippoZero
author_rank: Newbie
timestamp: April 18, 2024, 09:52:59 am
content: DVDD - 5vVCP - 17vVREF - 3.3vNFAULT - 340 mvIt's pulling nFault low

author: Psi
author_rank: Super Contributor
timestamp: April 18, 2024, 10:14:10 am
content: First rule of troubleshooting, check voltagesWhat voltage is VM?Your VCP voltage of 17V suggests VM must be around 10V but is that correct?

author: RippoZero
author_rank: Newbie
timestamp: April 18, 2024, 10:17:43 am
content: The datasheet specifies that nFault should be pulled up to DVDD if it's 5v logic, otherwise hocked up to external logic level. Since the logic level I'm using is 3.3v I made a goof here. Changed the pull-up resistor so it now bridges to 3.3v. The IC is now talking to the micro controller. Thank you very much Psi

author: RippoZero
author_rank: Newbie
timestamp: September 24, 2025, 11:21:26 pm
content: For the sake of anyone else that stumble upon this post in the future I should probably add that the capacitor on DVDD is too smal. I goofed when I typed the value into the kicad schematic. The datasheet states it should be 0.47 - 1 uf.
Motor keep on rotating for long time even if power off/motor pins short - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: April 08, 2016, 09:08:19 am
content: 1. I have purchaes a motor from local market. It don't have any part number on it(scratched out). Local market person syas it was used in earlier walkman.On internet I had checked my motor looks like this, but shaft is bit longer:http://www.aliexpress.com/item/hot-sale-15pcs-Mabuchi-Walkman-motor-repetition-machine-motor/32263326923.html2. This motor runs even at 3.3V with very good speed, ther is no big load on it just very small tyre. Currently I am running at 12V, load is around 800mA by motor & its load.Problem is when motor is stopped, then keeps on rotating after for long time. I want to stop motor at once when MCU stops PWM.I have alos tried by shorting the pins of motor manually, but even then it keeps on rotating.How to stop it at onceEdit: time change

author: Chalcogenide
author_rank: Regular Contributor
timestamp: April 08, 2016, 09:38:47 am
content: If you use an H-bridge to provide the pwm you can reverse the supply voltage on the motor pins so that it acts as a brake. An other solution might be to switch a resistor or a zener / TVS diode between the pins so that the voltage rises and energy is dissipated faster (but watch out for the breakdown voltage of the driving mosfet/chip/whatever) - this second option has its caveats and is typically slower.

author: danadak
author_rank: Super Contributor
timestamp: April 08, 2016, 12:51:11 pm
content: This might be useful -https://e2e.ti.com/blogs_/b/motordrivecontrol/archive/2013/10/18/the-art-of-stopping-a-motorRegards, Dana.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: April 09, 2016, 04:42:31 pm
content: Added a small mechanical braking system, now it is working fine.
Motor on a rotating mount [Solved, its called a "slip ring" ] - Page 1
Forum section: electronics / beginners

author: Sudo_apt-get_install_yum
author_rank: Regular Contributor
timestamp: January 15, 2019, 10:09:50 am
content: Hi all!So I’m doing a small project that requires 360 degree movement in two axes. I’ve designed it so the motor for Y-axis (tilt) is attached to the X-axis (pan).The problem is that the cables get all twisted...Is there a "module" type of a thing that can couple a bipolar stepper motor cable, 4-wires and 1A per phase?I know a thing like this must exist because it’s a common problem but I can’t seem to find any of the shelf type things...Worst case scenario ill make it myself using pogo pins and exposed copper traces on a PCB.I did solve a similar problem at a previous job by using two coils, one for the rotating mount and on for the static part (it was just for communication)

author: RoGeorge
author_rank: Super Contributor
timestamp: January 15, 2019, 10:16:48 am
content: In case you want to avoid mechanical friction, you can transfer the energy to the inner motor using the magnetic field, i.e. a disc shaped transformer placed at the mechanical joint.

author: beanflying
author_rank: Super Contributor
timestamp: January 15, 2019, 10:25:42 am
content: What you need is a Slip Ring. Used a fair bit in stage lighting for two axis movements (possible source of hardware for you)eBay auction: #323594909082or here is an exampleeBay auction: #282551915466I brought some of these earlier in the year to play with a single axis 360 degree movement.

author: Psi
author_rank: Super Contributor
timestamp: January 15, 2019, 11:28:52 am
content: Lots of slip rings are available on aliexpress as well.https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20190115032820&SearchText=slip+ring

author: beanflying
author_rank: Super Contributor
timestamp: January 15, 2019, 11:36:53 am
content: Just because it is Big CliveLook at the insides of the teardown and use some ideas on your own project.https://youtu.be/i3dHP6ehGY0

author: Sudo_apt-get_install_yum
author_rank: Regular Contributor
timestamp: January 15, 2019, 11:49:27 am
content: Thanks all for the suggestions; I learned the name for the component!I found a perfect slip ring at the alieexpress link above.I made a 3D model of it and added it to my assembly in solid works and it seems to fit perfectly fine!Case closed!
Motor run capacitor replacement - Page 1
Forum section: electronics / beginners

author: leppie
author_rank: Frequent Contributor
timestamp: March 01, 2016, 06:27:16 am
content: HiThe motor run cap on my AC has died. Spec/design calls for 1.5uF 450VAC (only reads 45nF now). Been doing some reading about what values I can use for a replacement as I cannot find the exact value, but it is still not clear to me. I can get 2uF 450VAC.As far as I can see, this is the fan motor:Would 2uF be OK, or would that possibly cause too much problems in the long run?Thanks

author: leppie
author_rank: Frequent Contributor
timestamp: March 01, 2016, 02:25:27 pm
content: Just went with a 2uF one. Cost all of ZAR8 (~US$0.50).I was quoted ZAR8000 (~US$500) for repair, by some people that clearly looked like they did not know what they were doing.Fan seems to be running OK, will see if any problems popup and get a proper valued one if needed.
Motor specifications for ornithopter - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: April 07, 2017, 12:39:11 pm
content: Hello everyoneI'm modelling an rc controlled ornithopter (artificial wing flapping bird) as part of my project,and I am an absolute beginner in the field of dc motors and I don't have a clue on what motor to use. The bird is having a total wingspan of about 1.3 meters ,and the frame weights about 50-100 grams. The bird is supposed to have a flapping freequency of 3 to 7 beats per second (about 500 rpm of crank),and I'm planning to drive the wing using a crank rocker mechanism. Here is the primary model of the bird I made using Solidworks. Can anyone please suggest what type of motor and other electronics should be used ?

author: Benta
author_rank: Super Contributor
timestamp: April 07, 2017, 02:22:42 pm
content: You'll need a gear motor at least.

author: ebastler
author_rank: Super Contributor
timestamp: April 09, 2017, 06:58:04 am
content: Have you modelled/estimated the force that will be needed to move the wings up and down? (Which will be dominated by the air resistance, I assume, but the weight and inertia of the wing structure may also be non-negligible.) I think you should start with a quantitative estimate of the torque you need from the motor, then take it from there.As a side note, it seems that your mechanical design can only flap the wings up and down. Don't you need some degree of freedom to tilt them (for less air resistance) before the up-stroke, then tilt/twist/rotate them back for higher air resistance before the down-stroke? Or maybe I have overlooked a degree of freedom in your model.
Motor speed control, suggestions? - Page 1
Forum section: electronics / beginners

author: PeterFW
author_rank: Frequent Contributor
timestamp: March 27, 2016, 05:21:39 pm
content: Hello!So... i am trying to build a magnetic stir plate that can run forwards and backwards since i need some "randomised agitation" of a liquid and i do not want to use air for several reasons.Build from spare/junk parts, so... as cheap as possible.An old PC Fan worked rather nicely for first experiements but it lacks torque and does not like to run backwards.All the old DC motors i have at hand all lack the ability to run at low RPM with enough torque.All the geared DC Motors i can find do not run at enough RPM.My old cordless drill motors with a planetary gear system are to long.I tought of hacking a hobby rc servo apart, that might work.What i have at hand is cheap L298 motor driver and some microcontrollers to control it, that is not the problem.Has someone another suggestion?Greetings,Peter

author: SeanB
author_rank: Super Contributor
timestamp: March 27, 2016, 05:44:13 pm
content: Microwave turntable motor will work. Run forwards and when you stop the next time it will run backwards. Just note that often you will find that the motors are not always 220VAC motors, but are often 40VAC motors, running off a power resistor on a PCB at the power entry, which has the input cable, the input filter and the power relay, along with the resistive dropper that provides motor power. just look inside the cover and you will find the circuit diagram for the microwave as well with the connections.Just use the turntable coupler and epoxy the magnet to it, and you get a few RPM of rotation at a respectable torque.
Motor Speed Control - Page 1
Forum section: electronics / beginners

author: DarkZero
author_rank: Regular Contributor
timestamp: May 22, 2017, 08:22:00 pm
content: Hi All!can i add bridge rectifier and thyristor instead of triac to the attached circuit and use it as a speed control for my 400v DC motor. and do i need to add a diode across motor like you would add it across relay.

author: tatus1969
author_rank: Super Contributor
timestamp: May 22, 2017, 09:09:07 pm
content: that circuit relies on an AC waveform that fires the triac at each cycle with an adjustable delay. For DC operation, consider a PWM circuit using a MOSFET or IGBT for power switching.Me talking stupid things...

author: Seekonk
author_rank: Super Contributor
timestamp: May 22, 2017, 10:25:09 pm
content: I've seen commercial speed controls that just full wave rectified the output of a triac speed control.

author: DarkZero
author_rank: Regular Contributor
timestamp: May 23, 2017, 07:17:29 pm
content: well i added a bridge rectifier instead of Rp and it works just fine its choppy on really low speeds but i can live with that
Motor start/run capacitor vs electrolytic - Page 1
Forum section: electronics / beginners

author: theoldwizard1
author_rank: Regular Contributor
timestamp: March 16, 2021, 06:39:36 pm
content: Electrolytic capacitor have polarity. Other types do not but are usually much smaller.What is different about AC motor start/run capacitors that they are not polarized ?

author: Gyro
author_rank: Super Contributor
timestamp: March 16, 2021, 06:53:26 pm
content: There is a an important distinction between the two motor capacitor types you mentioned....Motor Run capacitors are designed for continuous AC operation. The are film capacitors (normally Polypropylene), not electrolytics, so are fairly large for their capacitance.Motor Start capacitors are designed for very short duty, just long enough for an induction motor to spin up. They are Bipolar Electrolytic caps so are smaller for their (higher) capacitance values, but too small to handle the heat produced by continuous AC operation.EDIT: Bipolar electrolytics are available in smaller sizes - normally used for applications like audio signal coupling and speaker crossovers. Not all electrolytics are polarised (just most).

author: Siwastaja
author_rank: Super Contributor
timestamp: March 17, 2021, 02:41:58 pm
content: Simply put, the internal resistance varies all over the place between the capacitor types. You can model it as a resistor in series with an ideal capacitor. When current runs through that resistor, it heats up. But the internal resistance is distributed "everywhere" inside the capacitor.Higher internal resistance means higher power dissipation whenever the capacitor charges or discharges (i.e., current is flowing through it).Heat kills the capacitor internally, either gradually, or suddenly/catastrophically.The reason to use motor run or start capacitors is that they provide a second shifted-in-time phase for the motor, so that the windings can generate torque in two dimensions. One phase can only provide pulsating force in one dimension (let's call that X axis). Another phase, optimally 90 degrees apart (Y axis!) is needed to create the rotating vector (defined by sine and cosine). The capacitor creates this time-shifted second phase (not actually 90 degrees, but close enough for it to work) by storing and releasing energy. Within each storage and release event, there will be losses that heat up the capacitor.Run cap provides this second phase all the time. In start cap systems, the second phase is only available shortly, because even the crappy 1-dimensional pulsating force can keep the motor running once it has inertia. Think about 1-cylinder engine.Run capacitors charge and discharge at the mains frequency, i.e. 50-60 times a second, all the time, possibly for decades. Capacitors must have internal resistance low enough so they don't heat up internally.Start capacitors can be more lossy to save on cost and size because they see a few seconds of use at a time, and possibly just some hundreds of cycles within their lifetime.Always remember capacitors have current/power ratings as well because they are far from ideal.
Motor state sensor emulator - Page 1
Forum section: electronics / beginners

author: junkandshitandjunk
author_rank: Newbie
timestamp: February 21, 2022, 06:06:24 pm
content: hello, i need to build a motor sensor state emulator, so i need one input and two outputs, basically its a 24v dc motor with two optic sensors, i need to emulate. it works this way, machine drives motor until one optical sensor closes and other sensor opens then motor stops, after that machine drives motor again until sensors restores its beginning state, one open, other closed.What i need is idea of schematic for this task, soinput high, output 1 changes to low, ouput 2 changes to high, (after that input changes to low by other hardware)next machine run input high, output 1 changes to high, output 2 to low, (after that input changes to low by other hardware)this will be the loop.outputs will be just two optocouplers, input is 24V DC. How to achieve this without microcontroller?

author: jwet
author_rank: Frequent Contributor
timestamp: March 16, 2022, 03:02:16 pm
content: I ran into a really clever circuit for the door limits in my garage door opener. To adjust the stops at the bottom and top of travel, they use a little length of threaded rod- a lead screw and two adjustable end stop switches (could be opto's). This little lead screw run with the main drive motor while the drive motor is also driving the real door up and down. To adjust the door limits, you adjust this litlle model's limits swtiches. Very clever. It would seem like something like this cold work for you- a little gear motor, a threaded rod, a nut. 3d printing could make a really nice job of it. My 2 cents.

author: Ian.M
author_rank: Super Contributor
timestamp: March 16, 2022, 03:20:43 pm
content: That will do if the motor actually reverses. If it continues in the same direction, you'll need something that does *NOT* use a screw mechanism as repeated linear travel in the same direction is impractical.It gets far far more complex if you need the sensors to be adjustable for time and interval between their activation. While you could do something with overlapping 90 degree vanes clamped to a shaft driven by a gearmotor coupled to a CVT, its going to be quite a complex mechanism.Does the original equipment control the speed of the motor in any way? If it isn't a simple DC motor, run 'flat out' with no tacho or encoder feedback, any electronic solution will be much harder to implement.
Motor with six cables - Page 1
Forum section: electronics / beginners

author: Luximus Prime
author_rank: Newbie
timestamp: March 23, 2015, 12:05:08 pm
content: Hello,I have a motor that i got out of our old washing machine and I would like to use it for a project.I have no idea what to hook up to what though.I am used to the motors that you hook up to an AA battery and off ya go.Here is a link to some photos of the motor and a schematic that I found inside the washing machine:http://imgur.com/a/t6QCdWould you be able to help me find what connects to what? Will I need to buy anything?Thanks

author: Zero999
author_rank: Super Contributor
timestamp: March 23, 2015, 01:14:38 pm
content: This is pretty normal.2 & 3 is the field4 & 5 is the armature6 & 7 is a small generator which outputs a variable voltage/frequency, proportional to the motor speed.What kind of load are you planning to drive with this motor?Normally the field is connected in series with the armature but under light loads, it will cause over-speed and violent destruction.The field can be separately powered but it needs a much lower voltage than the armature, typically 6 to 12V and there needs to be some protection to cut the power to the armature, if the field is disconnected.
motorbike voltage regulator (1980 vespa) - Page 1
Forum section: electronics / beginners

author: Boschi
author_rank: Regular Contributor
timestamp: June 11, 2021, 03:07:54 pm
content: hi! I have recently got a Vespa primavera from the '80s, and I have some problems with its electrical side.It took a while, but I finally understood that this is a constant current generator, not a "normal" one. this is a bit of a problem, as I would like to upgrade the lights, you know, to be able to see stuff while I drive at night (i live in a quiet rural area)the two coils that I want to regulate are the ones circled. the other one is for the ignition and it already works well.the first thing that I thought of is to add an ac voltage clipper to both coils, basically a full bridge rectifier, an lm431, and a transistor, but its the brute force approach, it would work but it would be bulky, redundant (as I need one for each coil) and it will dissipate quite some heat, plus as ill probably need 12v I still need to rectify it and boost the voltage.the second thing that came to my mind is, would it be possible to just put in series with the coil a transformer? it would still close the circuit (so no prob with strange spikes of voltage o the coil) and if I use a double secondary transformer I would be able to have 12v AC to its output and (with few wiring modifications) still being able to use the standard 6v bulbs.the third thing (that came to my mind as I'm writing this) would be a triac pre-regulator with zero-crossing detection. a block diagram in the attachments.basically, if the capacitor's voltage is lower than a threshold it would do nothing and simply charge the capacitors, once that threshold voltage is reached, at the next zero crossing it would short the triac.as a 2 stroke engine (theoretically) it could spin up to 10K rpm, as there are 6 poles on the spinning disk holding the magnet it would mean (in the worst-case scenario) an ac frequency around 1Khzagain, I'm writing here in beginner because as a self-taught guy I don't really understand inductors (and transformers), also I would need help in matching the whole system / choosing the comparator/SCR.the third option would be ideal, even If I lose 1.4V of the bridge rectifier, but I'd like to hear other opinions and perhaps other ways to achieve my goals.Thanks for any input!
Motorcycle LCD screen - changing colors, refurbishing old display? - Page 1
Forum section: electronics / beginners

author: BariBari
author_rank: Newbie
timestamp: June 26, 2019, 09:53:08 am
content: Hey guys, someone with very basic electronics knowledge here, but interested in a project to do either by myself for fun or find someone to do it for me, for $. But I would like to know what's going on first. So here's what's up.My motorcycle has a pair of old school LCD displays, you can see it here -- and they have quite some years on them, the numbers/contrast on them is OK but the background/faceplate of the screen is looking sort of faded. Also, at night, they have the classic orange light which needs to be changed. There are 8 PLCC2 LEDs on those 2 displays, but the faceplate is still orange so not sure if the white PLCC2 will be enough?My questions is - is it possible to change the color of the faceplate, how complicated of a process would it be to do such thing? Please note that I'm very ignorant on this subject and my question might sound lewd to someone knowledgeable, I just want to make my gauges nicer
Motorcycle Remote-Start Trigger Too Short - Page 1
Forum section: electronics / beginners

author: Odin Vex
author_rank: Newbie
timestamp: November 28, 2021, 04:59:56 am
content: I've got an issue with a product that has a rather silly limitation:It's a motorcycle alarm kit that has a remote-start feature in it, but the remote-start triggeronly activates for 0.7s. Yes,0.7s, as if that's long enough to turn over some motorcycles. Trouble is,the manufacturer has not made this parameter adjustable. Motorcycles don't have the biggest batteries and if you're limited to short runs and low-driving time with something like 4Ah being drained of about 20mA/s constantly for an alarm, you needeverybit of power you can hold onto. So I'm trying to come up witha circuit that uses no powerat alluntil it is triggered, thenkeeps itself turned on for 5 seconds(maximum specification by manufacturer for starting time), thenturns itself off.Worst-case scenario, I'd get a 12V DC triggered relay powered continuously by the CDI, but I'd prefer a more automotive 'drop and replace' solution. I was hoping there was something similar to a 4 or 5-pin JD1912/JD1914 that would turn on from trigger (12V+), then quickly rob enough current to power itself for a set amount of time (adjustable or fixed at 5s, not picky). Any thoughts?I've attached a Black and White schematic and a horribly colored schematic for what I think will work with the extra relay and delay module.Side notes:I left some things out relating to the Aftermarket CDI, stock CDI/ECM, and Alarm, only the relevant stuff was included.I wanted the power to come from the Green/Yellow line because it is only closed to Ground when the Brakes or Brake-Lock is on. I won't want to Remote Start without that on, ever.I also wanted the Kill Switch to *always* have final say, a safety issue. I don't want a bum-pressed Remote-Start taking my fingers off while working on the backend.Some of you might notice the whole “Aftermarket CDI” bit. I want my Kill Switch to work for that too. Most aftermarkets just hook up to a live side and consume power when the key is on, even when the vehicle isn't running. I wanted it to run only when expected to, not to mention a quick-disconnect there too. Powering by relay also eliminates the load from the stock harness (fused). This also allows the Remote Start to with Aftermarket CDI (it man-in-the-middles the ignition elsewhere).*Edit* Removed attachments, re-thinking the kill-switch circuitry (considering placing the gray ahead of the kill-switch and pink+brown after the ECM on the red line).
Motorcycle Wiring Diagram for lighting - Page 1
Forum section: electronics / beginners

author: jackietan
author_rank: Newbie
timestamp: January 05, 2018, 03:30:32 pm
content: I have a question for Motorcycle lighting. I have draft a wiring diagram posted here:https://www.hdforums.com/forum/touring-models/1213320-harley-davidson-electra-glo.htmlElectra GloPurple (Three LEDs lighted on the left) / Black & Green (Negative) / Purple & White (Three LEDs lighted on the right)Existing lightRed (Brake) / White (Positive) / Green (Turn) / Black (Negative)

author: jackietan
author_rank: Newbie
timestamp: January 05, 2018, 03:34:50 pm
content: 1. Can I join both the Negative wire from Existing Light with the Electra Glo together?2. Can I combine the two Electra Glo wires and connect to Existing Light Brake and Running separately?

author: jeroen79
author_rank: Frequent Contributor
timestamp: January 05, 2018, 05:03:23 pm
content: That would short the brake and running lights so they will always light together.Add diodes before the join to keep the two lines separate.

author: rbm
author_rank: Regular Contributor
timestamp: January 05, 2018, 09:57:18 pm
content: Be careful. I did a quick search on the Electra Glo brake light kit and it is supposed to be used with a provided module. The module is supposed to adapt the lights to the existing HD wiring harness. I am not a HD knowledgable person but I would think that the wiring on the HD is Canbus and not old-school. So paralleling the Electra Glos onto the existing signal and brake circuits will most certainly upset the electronics on your bike and may do damage. Have you tried to follow the provided installation instructions?
Motorized slide controller that can also be operated by hand? - Page 1
Forum section: electronics / beginners

author: dog80
author_rank: Regular Contributor
timestamp: December 21, 2013, 01:55:42 pm
content: Most wood stoves have a sliding lever that controls the incoming air.The lever can be seen here at the leftmost position. It is situated right on top of the door.http://www.hotprice.co.uk/images/uploaded/Image/Amesti-Stove-Main-Image.jpgI want to control this lever by MCU. Also it would be nice to have the option to override the position chosen by the MCU and move the lever by hand. Is there any motor arrangement that allows this?

author: V_King
author_rank: Regular Contributor
timestamp: December 28, 2013, 01:20:03 pm
content: had a familiar stove in my previous house. the lever on top, was not of the perfect design and if left in the same place for longer period of time, would get sticky. You would need a strong motor to control it.If I were you, I would install a butterfly throttle between the stove and the chimney and control the exhaust. the control would be easy and all the mechanisms would be neatly tucked away. to override control you could just add two buttons or a pot, to fully open/close the valve.

author: owl_uk
author_rank: Contributor
timestamp: December 28, 2013, 03:49:07 pm
content: if you want to do something which is motor controlled but allows for a manual override there are lots of ways to do it. Some pointers for you:- stepper motors are useful because they can apply various amounts of torque (including none) and can go in both directions. They can also act as a brake. All of these things can be helpful for lever control type applications- you will probably need position encoders / sensors of some kind to tell you where your control is, then you can compare that to where you want it to be- a bit of play in the system is very useful in this kind of system. You could use some arrangement of springs or rubber belts or similar between your motor and the lever. This will allow you to move it slightly manually without having to move the motor. Your MCU can detect this movement. This is handy if (for example) your motor is acting as a brake at the time, because you can move the lever enough to tell the MCU that it needs to release the brake.- if you're not familiar with control theory you might need to read up on it a bit. When your output drives your input strange things can happen, like slow creeping from one end of the controlled range to the other, or sudden unexpected movements under a full moon on thursdays. If you find yourself doing lots of small adjustments to make a system seem to work, or become stable, then you need to understand the underlying control theory before you can be confident it won't give you a surpirse
Motorizing a wheeled bag - Page 1
Forum section: electronics / beginners

author: Axk
author_rank: Regular Contributor
timestamp: November 06, 2017, 05:18:36 pm
content: I'm thinking about motorizing a wheeled bag like this one:For reference the wheel diameter s 15 cm.Sorry if the question is too broad, but I'm not sure where to start from and if this is easily doable with readily-available parts (motors, controller, gearing) and without going too deep into motor theory thus this question.Any suggestions are welcome.Thinking of it handling 20 kg max at 4 km/h for 2h.Ideally the motor(s), electronics and battery should be as light as possible (say 2-3kg max).With all modern powerful hoverboards and such I suppose this should be possible but not sure where to start from. Hoverboards using BLDC motors I guess I can use BLDC as well.I guess the easiest would be hub wheels with built-in motors like those used in hoverboards because these don't require any additional gearing and can easily replace existing wheels. But the ones I can find online are all too heavy and/or powerful for my task.There are plenty of (non-hub) BLDC motors available with different sizes weights and power. I guess the easiest (second to wheel hub motors) would be to have 2 motors directly driving the 2 wheels on the bag but then how to control them, how to be sure a motor can provide enough torque at low speed to directly drive the wheels (they typically give voltage, power and rpm on aliexpress and ebay).They have readily-available controllers for BLDC motors but how do I match them with a particular motor (I realize some uC programming may be necessary).

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 06, 2017, 05:43:32 pm
content: Ben Heck made a video about building such a thing.....https://youtu.be/tAyWrJoVUbs
Motorola MC68008P10 current draw - Page 1
Forum section: electronics / beginners

author: janoc
author_rank: Super Contributor
timestamp: November 05, 2013, 04:57:41 pm
content: Hello,I am building a little retrocomputer for fun and the educational experience using a classic MC68008P10 chip in the 48pin DIP package. However, I was a bit surprised to see that the CPU draws about 170mA doing nothing - with just power and 4MHz clock hooked up. I can see it cycling through the address space, though.Is 170mA normal for this chip? It seems to run a bit warm too - about 50 degrees C. What are the normal, ballpark figures for this CPU? The maximum power dissipation in the datasheet is 1.5W, so at 5V it could potentially go up to 300mA, but still it seems a bit excessive to me.I am wondering about it, because I had some issues on the board with a mis-wired 74LS245 bus driver causing a short and I want to be sure that I didn't blow the pin drivers on the CPU.Regards,Jan

author: SeanB
author_rank: Super Contributor
timestamp: November 05, 2013, 07:11:19 pm
content: They do run toasty. I have done a mod on some older CPU's that ran very warm by using some thermal epoxy to fit a small DIP heatsink ( or for some 286 chips I was overclocking a little as big a heatsink as I could fit) to the top of the unit to drop the surface temperature by about 20C, which cooled them down a lot.

author: janoc
author_rank: Super Contributor
timestamp: November 07, 2013, 02:34:13 pm
content: Ah, thanks for the info. I guess I am too used to the modern CMOS parts that take a few milliamps tops and run cool. However, I haven't seen heatsinks on these CPUs in any of the Amigas or Atari STs that used them, so I guess it could be OK.I have even the larger MC68000 cousin in the ginormous DIP64 package (the largest DIP chip I have ever seen), but I haven't tested that one yet.J.
Motorola Moto X Motherboard Question - Page 1
Forum section: electronics / beginners

author: PatrickJones
author_rank: Newbie
timestamp: February 01, 2018, 04:40:55 pm
content: I accidentally ripped two of four connector pads off the motherboard of my phone when I tried to pry off the battery connector. I tried soldering them back into place, but ended up just destroying the battery connector and taking if off. Please see picture. Any way for me to fix it, or should I just give up? BTW, I have zero skills in electronics or soldering, as you can probably tell. Also, I can't seem to find a replacement battery connector for a 2015 Motorola Moto X Pure Edition phone anywhere. Any suggestions? Thanks.

author: CharlieEcho
author_rank: Regular Contributor
timestamp: February 03, 2018, 12:39:26 am
content: Replacement ribbon cables are on ebay. As are replacement motherboards. You can just swap one out if its the same carrier. Otherwise you'd have to transfer the components and hope the boad isn't damaged. Which apparently didn't go so well the first time around.Do you have phone insurance on your plan? If you do just hit the remains with a mallet a few times and then get it replaced.
motorola part number with a tek 465b - Page 1
Forum section: electronics / beginners

author: jsblues81
author_rank: Contributor
timestamp: February 26, 2022, 07:37:50 pm
content: Does anybody know the motorola part # for Q4102 on a 465b scope I believe the tek part is 052-034900. This is the -8v pass element in the power supply...thanks.

author: floobydust
author_rank: Super Contributor
timestamp: February 26, 2022, 08:56:01 pm
content: TEK465b Q4102 -8V pass transistor, 151-0349-00, hand selectedMJE2801 SJE924NPN 90W TO-127 60V 10A I think selected for higher hFE. edit: found in TEK 1982 ref bookhere.I see people usingMJE3055TGTO-220 package as a replacement.MJF3055same but in a plastic fullpack.Spherehas some but you must give your left arm.If the part overheats, look for shorted tantalum capacitors on that rail.

author: jsblues81
author_rank: Contributor
timestamp: February 27, 2022, 11:04:19 am
content: Thanks...just the info I needed.
Motorola SC80497P1 - Page 1
Forum section: electronics / beginners

author: StyxF2
author_rank: Contributor
timestamp: July 26, 2024, 06:22:36 am
content: Can anyone help identify the MCU in attached pic? I thought it was a Intel 8049 processor, but the connections are just getting to weird. Web searches dont bring up anything for a SC80497Some pinouts i've worked out:Pin 1 & 2: Crystal 3.579MHzPin 38 & 40: 5VPin 20 & 21: GndPin 39: Reset(?)

author: Benta
author_rank: Super Contributor
timestamp: July 26, 2024, 10:01:05 am
content: Motorola mask programmed microcontroller, most likely an MC6801 or MC6805 variant (the HC versions were not available in 1981).
Motors, feedback and microprocessor - Page 1
Forum section: electronics / beginners

author: The Magic Rabbit
author_rank: Regular Contributor
timestamp: March 05, 2016, 03:40:43 pm
content: I've obtained some motors from an old vinyl cutting machine. I'm not sure of the specification but I know they are servo not stepper, and they have an attachment on them that feeds back position to a control board. You can probably guess my next question...How do I use them!?!?I figured out that they are DC and so direction is a case of switching polarity. I am not sure how speed is controlled - I suspect PWM to move in increments.How do I connect to the position sensor though? Are they standard? Is it likely to be a single input wire and the others output? How would I go about determining this?Needless to say the motor is proprietary, and as such, has no useful information stamped on it.Sent from my XT1039 using Tapatalk

author: Simon
author_rank: Unknown
timestamp: March 05, 2016, 04:06:23 pm
content: It's going to be difficult to advise because obviously nobody knows what sort of position centre/encoder you have on the motor. At a guess I would say that you will get one pulse or more per revolution how long that pulses what voltage it is our total unknowns.My dad has a very nice record player and it is speed controlled it is a brushed motor I believe and there is an infrared transmitter and receiver in one module that a tab on the turntable goes past every time it does one revolution. So obviously the speed can only be corrected once every revolution may be if this is a cutting table motor it will have more steps in it so that it can have finer control over the speed as its more critical.

author: The Magic Rabbit
author_rank: Regular Contributor
timestamp: March 05, 2016, 04:56:30 pm
content: There's not much gearing outside the motor, so I'd imagine it has more integral brush pairs, or whatever will give it more refined movement.Having been doing some more digging, I've found the motor is a Hansen 116-33224-7 manufactured for GCC. They wont divulge any information about it though, so I'm wondering if the Hansen site might have some clues.Sent from my XT1039 using Tapatalk

author: awallin
author_rank: Frequent Contributor
timestamp: March 05, 2016, 08:38:24 pm
content: if it's a DC brush servo with an encoder you need something like this:http://www.geckodrive.com/geckodrive-brush-dc-drives.htmlthat drive takes step/dir such as those from Mach3 or linuxcnc parallel-port or other IO, or a dedicated controller like the one mikes-electric-stuff reviewed recently.A picture of the servo(s) might help identifying what they are.

author: Simon
author_rank: Unknown
timestamp: March 05, 2016, 08:47:27 pm
content: depending on how old it is it might just be output pulses. if only one direction is required then a dual output encoder is not neccesary or if it is dual output only one needs using. What will be more interesting is how many pulses per rev it outputs.