Chemelc, Yes, this circuit is for a power steering assist and at rest and normal straight driving, the motor is turned into a dynamic brake to resist bump steering.
Another tidbit of information is probably of little concern is that when the FETs were destroyed, I was testing them to see if they would fail, the OHV has 4 wheel drive and the differentials can be locked and when turning, there is a terrific bind and this causes the steering to try to go straight and requires a lot of power to counter act. Turning the wheels to full left or right is virtually impossible on pavement, but on sand or dirt, just hard.
richardb, the 555 in the schematic is driven by the oscillator via the trigger input and out drives a boost circuit for 25v for the upper FETs, it has a feed back to CV to control the voltage.
While checking the spec sheets of the LM2901n and LT1017, I noticed this application,(see attached) and I will modify my circuit to include it.
Gate Current is NOT an Issue for Mosfets.
Typical Gate Current on Mosfets is MUCH LESS than 1 uA.
But a GOOD Waveform, with a good Rise and Fall is ESSENTIAL.
DOES he Actually Have a GOOD SQUARE WAVE, Or is he driving with a TRIANGLE Wave?
A Triangle Wave will Create a LOT OF HEAT in the Mosfets.
I usually just drive my Mosfets wih a 555 and Never have any Problems.
Even at Quite High Frequencies.
Gate Current is NOT an Issue for Mosfets.
Typical Gate Current on Mosfets is MUCH LESS than 1 uA.
But a GOOD Waveform, with a good Rise and Fall is ESSENTIAL.
DOES he Actually Have a GOOD SQUARE WAVE, Or is he driving with a TRIANGLE Wave?
A Triangle Wave will Create a LOT OF HEAT in the Mosfets.
I usually just drive my Mosfets wih a 555 and Never have any Problems.
Even at Quite High Frequencies.
How many times do we have to say it, you cannot drive a mosfet fast using a pullup resistor. You need a proper driver to get this working without overheating, even a simple bjt complementary buffer will be better than this.
The gate capacitance of that mosfet is 3.3nF and for purposes of gate switching it will act even a little bit worse.
Thank you, I agree with your reasoning, but was concerned about the space required, I shall upload my files to ETO.It is my understanding pictures are to be uploaded to ETO and not hosted on third party sites. Due to the possibility of corrupt links or deletion.
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