My Motors got me to Tap into Radiant Energy

[prochiro]

Hi JohnStone
Thanks for the help. Got it going now although it throws my frequency/duty cycle thinking for a loop as it is inverted from PWM.

[JohnStone]

Hi Dana

I think you may have pin 3 and 4 the wrong way round:

http://www.vishay.com/docs/83740/sfh617a.pdf

Also I found out the hard way, you need a resistor between the MOSFET gate to ground to quickly switch off the MOSFET.

Regards
John

Sorry, my post above is not clear enough.
opto.jpg
Thus you can test the opto itself.

For connecting a FET remove LED. A FET gate is basically a capacitor. You can imagine on how to charge it and discharge it.
You can add to the circuit above a FET (connect gate to opto pin 4 and source to pin 3.
If output of opto switched off -> the gate will be charge via resistor -> FET switched on.
If output switched on -> the opto output sinks ALL current from resistor and additionally discharges the charge out of the gate - the FET switched off
opto FET1.jpg

There are different ways to wire an opto to a FET. This is just one way to do it.
IF any question please ask! It is essential to understand!

[john_g]

JohnStone
I have been trying to see how the SFH617A works by creating a small breadboard circuit. Cant get it to work. I set up the PWM which has a small led to show slow pulses and put that into pin one of the opto. Pin 2 goes to PWM negative. At this time I believe I have somewhat like what a mosfet with a wire to the base looks like. OK to here? Then on a separate power supply, positive to opto pin 3. Pin four goes to an led/resistor and back to negative. The led just stays on and does not blink like I think it should with the led in the PWM. What am I doing wrong. ?????
Dana

Hi Dana

I think you may have pin 3 and 4 the wrong way round:

http://www.vishay.com/docs/83740/sfh617a.pdf

Also I found out the hard way, you need a resistor between the MOSFET gate to ground to quickly switch off the MOSFET.

Regards
John

[JohnStone]

JohnStone
I have been trying to see how the SFH617A works by creating a small breadboard circuit. Cant get it to work. I set up the PWM which has a small led to show slow pulses and put that into pin one of the opto. Pin 2 goes to PWM negative. At this time I believe I have somewhat like what a mosfet with a wire to the base looks like. OK to here? Then on a separate power supply, positive to opto pin 3. Pin four goes to an led/resistor and back to negative. The led just stays on and does not blink like I think it should with the led in the PWM. What am I doing wrong. ?????
Dana

Hi Dana,
Not sure what output you have at generator side. Is it source/sink or sink only? The opto input might be dead now?
In your report a resistor is missing at opto input. It needs to be operated like normal LED. Calculate the resistor to let 10...20mA to flow through the led.

Given your generator output is being driven by 12V calcualte (12V-1.6V)/20mA = 0.52 kOhm = 520 Ohm (1KOhm will do for test as well)

Connect for driving opto:
12V -> resistor -> opto pin 1 -> opto pin2 -> generator output.
[B]

Consult this animation I found for you in internet:

Additionally to pic you might want to connect a LED in prallel to the output pins of opto.

FYI: Transistors operate as well if you interchange emitter (arrow) and collector but they perform worse. Please check correct connection of pin 3 and 4 at opto.

JohnS

EDIT: for more details see post

[Cornboy 555]

Switching batteries.

Battery Isolators | Solid State Relays | ORing Diodes

Maybe off topic, but might be something for future.

Regards Cornboy.

[prochiro]

Sfh617a

JohnStone
I have been trying to see how the SFH617A works by creating a small breadboard circuit. Cant get it to work. I set up the PWM which has a small led to show slow pulses and put that into pin one of the opto. Pin 2 goes to PWM negative. At this time I believe I have somewhat like what a mosfet with a wire to the base looks like. OK to here? Then on a separate power supply, positive to opto pin 3. Pin four goes to an led/resistor and back to negative. The led just stays on and does not blink like I think it should with the led in the PWM. What am I doing wrong. ?????
Dana

[Cornboy 555]

RS.

Thanks for sympathy. Fogs are lifting but it takes time to disappear.

Regarding current sensors:
This is an addon for safety protecting our FETs. We should start keeping drivers simple and loading them with less load and voltage first. Do not get lost in secondary tasksAnybody may do the same but on own risk. There is no general recommendation availably yet.

Let's focus on drivers and get them running.

BTW:
For electronic enthusiasts herein: RS electronics offer a free program for schematics and PCB layout (full version). DesignsparkPCB
Quite big library and you can add own components easily. Schematics is quite easy to learn!!!!
Regarding components: You may decide to choose - directly from designspark - online out of RS stock and get a quotation for parts instantly.
They sell the coolMOS FET suggested and the Micrel driver (sugested by Cornboy) as well.

I will draw my next schematic in Designspark. So you will get BOM along current prices.
JohnS

Hello John, I mainly buy parts from RS but have not been game to even look at designspark, once again, wwhhhooooosh, over my head, but maybe if you go this way i can follow.

It's feeling more like home to me.

Thanks john,

Regards Cornboy.

[JohnStone]

Hello John Stone, first of all, I was very sorry to hear about your some problem for which for the time being your motor project is on hold. We pray all the problems will be behind you very soon.

Thanks for sympathy. Fogs are lifting but it takes time to disappear.

Regarding current sensors:
This is an addon for safety protecting our FETs. We should start keeping drivers simple and loading them with less load and voltage first. Do not get lost in secondary tasksAnybody may do the same but on own risk. There is no general recommendation availably yet.

Let's focus on drivers and get them running.

BTW:
For electronic enthusiasts herein: RS electronics offer a free program for schematics and PCB layout (full version). DesignsparkPCB
Quite big library and you can add own components easily. Schematics is quite easy to learn!!!!
Regarding components: You may decide to choose - directly from designspark - online out of RS stock and get a quotation for parts instantly.
They sell the coolMOS FET suggested and the Micrel driver (sugested by Cornboy) as well.

I will draw my next schematic in Designspark. So you will get BOM along current prices.
JohnS

[Lightworker1]

Thanks for the hint. I will evaluate th 30A version. This is no decision regarding final component.
The carrier with ASC709 is a choice as well

Hello John Stone, first of all, I was very sorry to hear about your some problem for which for the time being your motor project is on hold. We pray all the problems will be behind you very soon.

[Lester444]

Hi Lester,
I agree with your concern and experienced it at a scope based current meters. I own such an old pet (Tectronix) and it proves you to be true.
On the other hand we may consider:

• This monolitic all in one component in automotive grade (1.5% accuracy) might be an advance compared with former makes.
• We do not want to measure exactly but to protect and thus it is not important if we stop current at 30A or 35A as long we prevent running FETs at maximum ratings.

Component: ACS714
Breakout board I prchased: here

Consult: this

I will go ahead and test it.
--------------------------------
@ALL not being gurus in electronics! Do not fall into despair! We need to discuss this on this level. You will get solid instructables later on.

That looks great John!

[Cornboy 555]

Automotive, yes please!

Hi Lester,
I agree with your concern and experienced it at a scope based current meters. I own such an old pet (Tectronix) and it proves you to be true.
On the other hand we may consider:

• This monolitic all in one component in automotive grade (1.5% accuracy) might be an advance compared with former makes.
• We do not want to measure exactly but to protect and thus it is not important if we stop current at 30A or 35A as long we prevent running FETs at maximum ratings.

Component: ACS714
Breakout board I prchased: here

Consult: this

I will go ahead and test it.
--------------------------------
@ALL not being gurus in electronics! Do not fall into despair! We need to discuss this on this level. You will get solid instructables later on.

Hello John and Lester, you guys are doing some great work here, Thanks.

I LOVE the words " AUTOMOTIVE GRADE " because it's normally made to withstand vibration, being inside a hot vehicle, etc, etc.

Regards Cornboy.

[JohnStone]

JohnStone
The
ACS714LLCTR-50A-T

is a 50 amp version.??????????????? Digikey has them at 1.80 USD.
Also the
ACS709 Current Sensor Carrier -75 to +75A


breakout board is same but heavier, also not a lot of money. These can also be cheap amp measuring devices.
Dana

Thanks for the hint. I will evaluate th 30A version. This is no decision regarding final component.
The carrier with ASC709 is a choice as well

[prochiro]

JohnStone
The
ACS714LLCTR-50A-T

is a 50 amp version.??????????????? Digikey has them at 1.80 USD.
Also the
ACS709 Current Sensor Carrier -75 to +75A


breakout board is same but heavier, also not a lot of money. These can also be cheap amp measuring devices.
Dana

[JohnStone]

Hi Lester,
I agree with your concern and experienced it at a scope based current meters. I own such an old pet (Tectronix) and it proves you to be true.
On the other hand we may consider:

• This monolitic all in one component in automotive grade (1.5% accuracy) might be an advance compared with former makes.
• We do not want to measure exactly but to protect and thus it is not important if we stop current at 30A or 35A as long we prevent running FETs at maximum ratings.

Component: ACS714
Breakout board I prchased: here

Consult: this

I will go ahead and test it.
--------------------------------
@ALL not being gurus in electronics! Do not fall into despair! We need to discuss this on this level. You will get solid instructables later on.

[Lester444]

Well you are right!
I did not focus on this fact but to the digital function. In fact I ordered this sensor. It is contactless (hall effect), lowest resistance and replaces a shunt directly.
Regarding digital part. Is there a smarter way to perform? Single chip? We approach a complexity where we need PCB.

The link doesn't work.

If you use a linear hall sensor then you have to worry about calibration, maybe once every month or even more often than that!!! Don't trust drift figures in the datasheet, it is not tested 100%. Trust me when I say that!

Passives are superior in this regard because they stay calibrated for a very long time. No worry, stay happy.