audioguru2
- Apr 6, 2004
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Hi,
That's a very fast opamp with a high input impedance. It will have no problem with a single supply.
You could use a 10V low-dropout regulator to power it and its oscillator and complimentary emitter-followers that drive the Mosfets' gates.
But the very limited spec sheet doesn't show how much the output swings in your application for driving emitter-followers, it spec's only a 100 ohms load. Your Mosfet gates will probably be driven to about 1.5V and 8V, which is good enough.
That's a very fast opamp with a high input impedance. It will have no problem with a single supply.
You could use a 10V low-dropout regulator to power it and its oscillator and complimentary emitter-followers that drive the Mosfets' gates.
But the very limited spec sheet doesn't show how much the output swings in your application for driving emitter-followers, it spec's only a 100 ohms load. Your Mosfet gates will probably be driven to about 1.5V and 8V, which is good enough.
Ante, I am pleased to say that I can get all of Farnell components ;D ;D ;D. Actually to say pleased is an understatement. They sent me their catalogue, and their catalogue on CD. their catalogue is in three parts well over 2000 pages combined. There CD is set up for business use, and everything in the CD and catalogues refers to me as a business customer, and there is nothing referring to me as a electronic hobbyists or any think along those lines. I'm beginning to wonder if I have done the wrong thing ???. I was expecting that thay would want me to pay for the catalogues, considering I did not have a business, which is fair enough 
. Well I guess all I can do now is,be happy that I can order in the components that I need. I was having a hard time logging onto Farnell sites and was constantly getting errors when navigating their site for suitable component, so I gave up and looked elsewhere. That was when I found the component I posted, unfortunately Farnell doesn't have a listing for it. I'm sure it would be very unlikely, that they wouldn't have other suitable components for this project. I didn't really expect the (TSH31) would be ideal, although it would have been good, I was just hoping that I was on the right track. More than likely I have downloaded a datasheet, for a component that is perfect, and don't realise it :-\. Well I am patient, and I'm slowly learning, so I shouldn't really expect more than that ;D.
Thanks ante, audioguru.
. Well I guess all I can do now is,be happy that I can order in the components that I need. I was having a hard time logging onto Farnell sites and was constantly getting errors when navigating their site for suitable component, so I gave up and looked elsewhere. That was when I found the component I posted, unfortunately Farnell doesn't have a listing for it. I'm sure it would be very unlikely, that they wouldn't have other suitable components for this project. I didn't really expect the (TSH31) would be ideal, although it would have been good, I was just hoping that I was on the right track. More than likely I have downloaded a datasheet, for a component that is perfect, and don't realise it :-\. Well I am patient, and I'm slowly learning, so I shouldn't really expect more than that ;D.Thanks ante, audioguru.
How about this IC. I can get it, and it is very reasonably priced. And if it is suitable, I'm keen to get the soldiering iron fired up, and happy to stop looking at datasheets.
Businessman ante, can you start a business by ordering in four components ;D. Maybe the oil companies have heard of my invention to, and want to buy the patents, I will start the bidding at $1 million, do I here $2 million 8)
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View attachment 35829
Businessman ante, can you start a business by ordering in four components ;D. Maybe the oil companies have heard of my invention to, and want to buy the patents, I will start the bidding at $1 million, do I here $2 million 8)
View attachment 35829
Ante, it has been very difficult to try to find, a IC that is reasonably priced and has the features we need. I have been very reluctant to choose one of the more expensive ICs, because of my inexperience, and I have to design the PCB. I haven't used surface mount chips before, and the mistakes that I am likely to make could become very costly. It seems the lower cost chips with the features we need, require low voltage supply. Wouldn't it be possible to just add a voltage regulator, or a zener diode and a resistor, to drop the voltage down for the IC. Or if we replaced the existing 9V regulator to an adjustable one, to give us 8V or a little less, the 555 IC will function find on this voltage, but I would expect this will upset the values of the rest of the components. I also found a fairly high-powered MOSFETs, that is very inexpensive that am hoping I can use ;D, I have attached the datasheet for it ???.
23061_FDP7030L.pdf
23061_FDP7030L.pdf
Well, as far as I can see the pin numbers matches on the op-amps. C1, C2, L1 is a protective filter which is supposed to
View attachment 35846
View attachment 35846
Yes ante, I did notice the mistake on the regulator. I am sure you just done that to test me ;D. I noticed it when I thought of changing it to an adjustable regulator. I also thought of using diodes to drop the voltage, I strung a few of them together to see how much the voltage would drop, then I thought it may be a bit of a rough way to go. It tells me on the datasheet for the(AD8061) that it is not a good idea, to run it at maximum voltage for long periods of time. Maybe the modifications that I made, will work OK what do you think. I also changed the power supply to the (ICL7667) should this work OK, I was thinking that I may need to experiment with higher voltage, so I will also have to consider the voltage ratings of the capacitors. Now I don't know if this will work or even if I need to do it, if I was to add a diode from the 9 V supply, and a diode from the 5 V supply and joined the 9v and the 5v together, this would give me 11.8V, to supply voltage to the(ICL7667) as to not upset things too much. So basically your circuit is still functioning as it had originally did, in respect to power supply. We've just improved it with a better amplifier and supply the amplifier with its ideal voltage .
View attachment 35847
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View attachment 35847
audioguru2
- Apr 6, 2004
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Hi Dazza,
Are you going to use an ICL7667 driver from Farnell? Good. It needs only a 0.8V to 2.0V TTL input voltage (but can take much more), and your AD8061 opamp used as a comparator is fully spec'd for a 5V TTL supply. So why not just use a 78L05 5V regulator for the AD8061?
The AD8061 works with input voltages from 0V to only 3.2V when using a 5V supply, so those input voltages should be reduced by adding a resistor to ground at its pin3, and changes to the adjustable reference (PWM control) voltage at pin2.
Hi Ante,
I don't like the D3 and D9 zeners which appear to feed positive load spikes directly into the outputs of the ICL7667. Since the ICL7667 has such a low output impedance, I think that the little D6 and D10 will blow first.
All that D5/7 and D8 are going to do is to add capacitance to the gates (and we don't need it).
Therefore let's get rid of all those zeners and diodes.
Most power Mosfets have a huge zener (and its reverse-bias diode) from drain to source.
Are you going to use an ICL7667 driver from Farnell? Good. It needs only a 0.8V to 2.0V TTL input voltage (but can take much more), and your AD8061 opamp used as a comparator is fully spec'd for a 5V TTL supply. So why not just use a 78L05 5V regulator for the AD8061?
The AD8061 works with input voltages from 0V to only 3.2V when using a 5V supply, so those input voltages should be reduced by adding a resistor to ground at its pin3, and changes to the adjustable reference (PWM control) voltage at pin2.
Hi Ante,
I don't like the D3 and D9 zeners which appear to feed positive load spikes directly into the outputs of the ICL7667. Since the ICL7667 has such a low output impedance, I think that the little D6 and D10 will blow first.
All that D5/7 and D8 are going to do is to add capacitance to the gates (and we don't need it).
Therefore let's get rid of all those zeners and diodes.
Most power Mosfets have a huge zener (and its reverse-bias diode) from drain to source.
Audioguru,
OK, low component count is good. I only put them there since I found them on some app sheet that many years ago where they where said to protect the mosfets (BUK416). If you say they are not good for this circuit, so be it. One question: isn
OK, low component count is good. I only put them there since I found them on some app sheet that many years ago where they where said to protect the mosfets (BUK416). If you say they are not good for this circuit, so be it. One question: isn
audioguru2
- Apr 6, 2004
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Good idea Ante!
The 555 will work fine on 5V, and the attenuating resistor for the opamp won't be required. So a 78L05 for both.
Dazza's Mosfets are not very powerful, probably better ones can be found.
The ICL7667 can drive many Mosfets but is supply line filtering must be increased.
The 555 will work fine on 5V, and the attenuating resistor for the opamp won't be required. So a 78L05 for both.
Dazza's Mosfets are not very powerful, probably better ones can be found.
The ICL7667 can drive many Mosfets but is supply line filtering must be increased.
Audioguru,
Questions:
Which characteristics to look for when hunting for mosfets besides cheap? ;D The FDP7030L have very low RDSon and can handle 30A (300A pulse) 125W and so on, what do you think is the draw backs? What exactly do you mean,
Questions:
Which characteristics to look for when hunting for mosfets besides cheap? ;D The FDP7030L have very low RDSon and can handle 30A (300A pulse) 125W and so on, what do you think is the draw backs? What exactly do you mean,
audioguru2
- Apr 6, 2004
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Hi Ante,
Soon I'll be huntimg for Mosfets and I'll let you know how I decided on one. My catalog has about 1000 Mosfets and the price list is separate from the spec's. Therefore it will be difficult to choose.
I will probably make a list of Mosfets that have the spec's that I need, and when I see their prices then I'll compromise the spec's, and then I'll select the cheapest one. I'll probably end up using more paralleled cheap mosfets than I originally planned.
The "supply line filtering must be increased" for the ICL7667 because it will draw high current pulses from the supply when it quickly charges and discharges the total high capacitance of the gates of multiple Mosfets. Plus the few-hundred mA current pulses that it draws though itself during switching.
Soon I'll be huntimg for Mosfets and I'll let you know how I decided on one. My catalog has about 1000 Mosfets and the price list is separate from the spec's. Therefore it will be difficult to choose.
I will probably make a list of Mosfets that have the spec's that I need, and when I see their prices then I'll compromise the spec's, and then I'll select the cheapest one. I'll probably end up using more paralleled cheap mosfets than I originally planned.
The "supply line filtering must be increased" for the ICL7667 because it will draw high current pulses from the supply when it quickly charges and discharges the total high capacitance of the gates of multiple Mosfets. Plus the few-hundred mA current pulses that it draws though itself during switching.
audioguru, yes I will be getting the components from Farnell. The MOSFETs (FDP7030L) is 100A 30V, this is what it is listed as, in Farnell CD catalogue. And on the datasheet I have ???.
ante, I'm just trying to get as much flexibility as I can. If I needed to experiment with voltage up to 24V it would be good, to not have to come back and modify the circuit. So a 5V regulator to supply(NE555N) and the(AD8061) so what would be best to use for (ICL7667) a 9V would give me a little headroom, considering my supply voltage is 12V or would it not matter, using a 12V regulator ???.
The voltage supplies the path for the current to flow through the water, this makes sense to me, this is why I'm thinking I may need to experiment with higher voltage. Does this sound right to you.
The components surrounding IC2 and IC4, are they going to be affected, now that they are being supplied 5V ???.
The regulator for(ICL7667) what should its current rating be.
ante, I'm just trying to get as much flexibility as I can. If I needed to experiment with voltage up to 24V it would be good, to not have to come back and modify the circuit. So a 5V regulator to supply(NE555N) and the(AD8061) so what would be best to use for (ICL7667) a 9V would give me a little headroom, considering my supply voltage is 12V or would it not matter, using a 12V regulator ???.
The voltage supplies the path for the current to flow through the water, this makes sense to me, this is why I'm thinking I may need to experiment with higher voltage. Does this sound right to you.
The components surrounding IC2 and IC4, are they going to be affected, now that they are being supplied 5V ???.
The regulator for(ICL7667) what should its current rating be.
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