Delta Pulse

[mohandes]

Hi look it

hi thanks
please put for me the lcd pcbs and connection to this board,i download it from :
http://www.teknolojiekibi.com/yeni/i...p?topic=2527.0
thanks
it is this pcb

[Nicolas]

hi thanks
please put for me the lcd pcbs and connection to this board,i download it from :
http://www.teknolojiekibi.com/yeni/i...p?topic=2527.0
thanks
it is this pcb

[ATTACH]26751[/ATTACH]

Hi yes

look it you find the connection.

And make attention to change RX by Two pot 10 Kohm to calculate the values exactly for RX. maybe no see the program. Every type of LCD have values for RX



Good luck friend

nicolas

[mohandes]

many thanks friend
very nice,
please put your pcb design here(lcd pcb), i can not find it

regards and cheers

[Nicolas]

many thanks friend
very nice,
please put your pcb design here(lcd pcb), i can not find it

regards and cheers

Hi pardon

Everything is in this forum or Turkish Forum. Just look for it
But not too bad prefer

http://www.kounooz.com/vb/showthread.php?t=1220
http://www.kounooz.com/vb/showthread.php?t=898
http://kounoooz.his-forum.com/t2580-topic
http://www.youtube.com/watch?feature...&v=7Nj1FL2R3yY

But with some adjustments for us and especially our programming

[mohandes]

Hi pardon

Everything is in this forum or Turkish Forum. Just look for it
But not too bad prefer

http://www.kounooz.com/vb/showthread.php?t=1220
http://www.kounooz.com/vb/showthread.php?t=898
http://kounoooz.his-forum.com/t2580-topic
http://www.youtube.com/watch?feature...&v=7Nj1FL2R3yY

But with some adjustments for us and especially our programming

thanks my friend
best wishes

[g.s]

Good evening...
Lately I have a notion that power supply for delta It is not effective..
I have prepared a figure to see the THINK..
what is your opinion about this ?? You might be better this way ..

[kt315]

non-working schematic. seems very strange for me. what you want to say by this? DP has good power supply and needs in only good batteries.
no need to change power part, waste your time on something another.

[g.s]

Can you explain kt315 what is the operating voltage to amp ???
I'm confused ????.. is +5 v and-5v ??? is the +12 v end +2v what is ultimately..

[kt315]

if reference level is -12V (minus clamp of battery) then for opamp we have +E=+12V, -E= 0,6+0,6 = +1,2 V
if reference point is GND then for opamp we have +E=+(12-1,2)/2=+5,4, -E=-(12-1.2)/2=-5.4.

I have to change reference level to +12V... this will be more right for this schematic... my mistake that I copied Bulgarian one straight out...

[g.s]

GOOD MORNING KT315 Can you explain THE BENEFIT IN HIS POWER..

[kt315]

a mos-fet gate has a comparatively big capacitance ~1000pf. if you want to encrease of speed of switching, from open to close state, you need also speedy recharge the gate capacitance. this your circuit must do it.

[kt315]

in your kopilku znanij, drug.

Posted by: Carl-NC (---.ipt.aol.com)
Date: December 25, 2001 01:43PM
Merry Christmas tech heads!
Question for all, but mainly for Eric. The main switching transistor (I'll call it Tr1) for the coil needs to turn off as quickly as possible. On some designs this transistor is driven directly by a logic gate, on others there is additional circuitry between the logic and Tr1.
Sometimes the additional circuitry is a CE amp with Tr1 driven off the collector, thus a collector resistor passively turns Tr1 on and the CE transistor actively switches it off. This is fine because turn-on time is not tremendously important. Call this method 1.
Sometimes there is a follower stage driving Tr1, thus the follower transistor turns Tr1 on and a pull-down resistor passively turns it off. Now turn-off time depends on the time constant set by the pull-down resistor and all the parasitics. Call this method 2.
I originally built my proto-PI with method 1. For funsies, I flipped things around to use method 2. My turn-off transient on the gate of Tr1 went from 0.5us (method 1) to 10us with a 1K pull-down and 3us with a 100R pull-down. This mostly just shifted out the exponential decay in time, but there was also a slight degradation in the decay as well. Not much, but it is observable on the o-scope.
The only design I've seen (that I can think of) that uses method 1 is Mark Stuart's Microcontroller PI project. Method 2 is used in other project designs, the SMPI, CS-7, and one (or more) of Eric's designs. My question is: How much does this matter? Is the actual turn-off of Tr1 dominated by charge transfer internal to the device?
Happy holidays,
Carl
Re: Coil switch

Posted by: Eric Foster (---.ipt.aol.com)
Date: December 26, 2001 03:34PM

Hi Carl,
Even the method of switching the power transistor is interesting, as there are so many inter-related factors. Assuming for most applications nowadays that Mosfets are used, there are, as you say, various methods of driving them. Strangely, although Mosfets are devices with a very high input impedance, the drive to them is recommended to be from a low impedance source. This is because the parasitic input capacitance is quite high, at around 1500pf, for the IRF740 types, and you need a low impedance to charge and discharge this capacitance quickly for efficient switching operation. As you have outlined, there are various ways to do this, and the question, at the end of the day, does it matter?
In a PI detector, we are concerned with driving a current though a coil for a short period of time, and then switching it off cleanly and rapidly. Any switch-on delays do not really matter, as the growth of the current is limited by the coil’s inductance. This delay, before the current reaches its maximum, will likely be several orders of magnitude slower than any delay caused by the capacitance and drive impedance of the Mosfet. At switch-off, we need to examine things in a bit more detail. To get the best eddy current response from an object, the switch-off of the field from the coil, needs to be at least 5 times faster than the object time constant. Obviously, if the switch-off is the same length of time as the time constant of the object, then there will be no signal to observe. At the point where the drive pulse to the gate is terminated, nothing much happens initially, as the gate retains the voltage on its capacitance. This capacitance will then start to discharge through the drive circuit impedance. On many of my circuits, including the Aquastar, this is simply a 100R resistor to the source. The turn-on is achieved by a PNP transistor that connects the gate to the drain supply via a 47R resistor. The resistive divider pots down the drive voltage so that no more volts than is necessary for proper switching is applied to the gate, otherwise it will take longer to discharge the gate capacitance. The discharge time constant is 0.15uS, giving a total discharge time 0.75uS, so this is more than enough speed for a treasure hunting PI. However, the gate voltage does not have to fall all the way to zero, but only to the gate threshold voltage, where the Mosfet just ceases to conduct; about 4V max for the IRF740. Using a 15V supply to the Mosfet and using the above circuit arrangement to maximum gate turn-on voltage is 9.5V, hence the time to reach the turn-off volts is only about one time constant, which takes us back to 0.15uS. Now, if we look at what happens in the drain/coil circuit at the point of cut-off of the Mosfet. Inductors don’t like a change of current, so the energy stored in the magnetic field will collapse and try to induce a voltage to keep the current in the coil flowing at the value it had just before switch-off. This is why we get a high voltage appearing across the coil at this point in time. The Mosfet is now a very high resistance and, if unrestrained, the coil voltage could reach over 1000V. However, the Mosfet has a breakdown, or avalanche voltage, which in the case of the IRF740, is about 400V. The coil voltage quickly rises to this level and then the Mosfet drain/source junction breaks down, and further voltage rise is prohibited. The Mosfet is then a low impedance across the coil during this high voltage period, which gives another, rather longer time constant. If you insert a small (0.1R) current monitoring resistor in the coil circuit and look at the waveform on a scope, you can see the current ramping down linearly for the duration of the high voltage pulse. As soon as the coil voltage falls below the 400V, then the Mosfet becomes a high impedance again, and it is now the duty of the damping resistor to absorb the rest of the energy: yet another time constant. Only after everything has settled down, including the recovery time of the first receiver amplifier, can we then look at the microvolt signal levels from objects at some distance from the coil. The delays from whichever type of Mosfet drive circuit used, only make a very small contribution, in my experience.
The things that have a major effect on the field switch off time are 1) the coil inductance, 2) the coil current. 3) the breakdown voltage of the Mosfet, and 4) the capacitance of the coil/cable circuit. However, these will keep for another time.
Eric.
Re: Coil switch

Posted by: Dave Johnson (---.tnt2.prescott.az.da.uu.net)
Date: December 26, 2001 11:14AM

Dear Carl,
When the collector turns off, you're expecting to get this whopping voltage spike (unless it's a Fisher type pulse unit). C-B Miller effect will stretch out the off-transition unless you keep the base as close to a short circuit as possible.
Back when I was doing PI I generally preferred bipolar switching transistors to MOSFETS because for a given on-resistance, they have a lot less capacitance. This makes for a quicker decay when the flyback pulse finally collapses. However, during the last 10 years, MOSFETS have gotten a lot better, whereas bipolars are about the same, so I suppose that the bipolar advantage may not be so great any more, and may have vanished entirely.
Most PI topologies (again, the Fisher is different) have a preamp that "looks into" a damping resistor shunted by clamp diodes, without any active circuit elements. Thus, the damping resistor dissipates energy during the transmitter on-time. By switching the damping resistor out of the circuit during the on-time, this waste of power can be eliminated.
Another problem with the conventional topology is that when the receive voltage drops below the forward bias voltage of the diodes, the damping resistor is no longer in parallel with the coil (i.e., no longer performs its damping function) but is still in series with the coil, impairing the preamp noise figure. Using some combination of fixed and/or actively-timed switching, it is possible to keep a damping resistor in the circuit during the receive period, and to switch the preamp directly to the coil, improving noise figure.
In many cases the extra circuitry won't produce results that make it worth the trouble. But, in some cases it may.
The Fisher topology does keep the damping resistor in the circuit and does switch the preamp directly to the coil; however, in the Fisher design that's easy to do with a CMOS transmission gate because the Fisher system has no voltages higher than a diode drop beyond the 5 volt power supply rails. Because the preamp is seeing only small signals, it can be operated in the linear region without saturation-- in fact, the preamp can be a Class A common-emitter transistor, allowing lower noise and power consumption than can be achieved with integrated circuit preamps.
By the way, this is not a sales pitch for the Fisher topology. That topology does have the advantage of power efficiency (as explained in the Fisher patent), with battery drain typically 15-30 mA. However, this (nearly) VLF-like efficiency is effective only over a narrow range of target conductivities. The Impulse, for example, is hot on nickels, but is downright muddy on a silver dollar-- the consequence of keeping the on-time short enough to have the energy stored in the field rather than dissipated in the coil as heat. On the other end of the conductivity scale, the low rate of change of voltage during the flyback period means that there is poor sensitivity to the lowest conductivity targets (gold chains, etc.) which is a disadvantage in many applications. I mention the "Fisher topology" because it's what I'm most familiar with, it is notably different from the other PI machines, is easy for an experimenter to build, and is described in a patent so an experimenter has a starting place. It is also possible that a PI design which was intermediate between the conventional topology and the Fisher system might prove to have worthwhile benefits.
Although the Fisher system probably cannot serve as the basis for a modern high-performance PI-only machine, the topology lends itself well to hybrid PI/VLF/MF designs using an induction balance searchcoil, as explained in the Fisher patent. This could possibly give the Fisher system a new lease on life.
--Dave J.
Impulse

Posted by: Eric Foster (---.ipt.aol.com)
Date: December 26, 2001 03:31PM

Hi Dave,
I guess you must be the designer of the Impulse electronics? I didn't think it had a triangular current waveform, but the other day I connected a small resistor in series with the coil on a Impulse, and sure enough, it has. All in all, it is a design with lots of innovative features and it is a pity that it wasn't developed further.
Eric.
Re: Coil switch

Posted by: Carl-NC (---.ipt.aol.com)
Date: December 29, 2001 10:56PM

Thanks guys... took me a while to thoroughly read your replies.
Eric, one thing I might debate is the MOSFET threshold. This is a DC parameter, when you're slewing the gate hard (even with active pull-down) there is a delay from getting the carriers into or out of the channel region. This is not the gate capacitance, but I believe more like a bipolar's forward-bias diffusion capacitance. I've always thought it might even be desirable to slew the gate to a negative voltage for faster turn-off but, as you said, this is all probably excessive.
The reason I asked is that I am laying out the PCB for my everything-adjustable platform PI design. In the true spirit of this design I am making the switch work either way.
Dave, I've also thought about switching out the diode clamp resistor. As you say, it's just a noise source on the input to the preamp. With my current design it's no big deal, but there are some hotrod amps that are less than 1nV/rtHz input-referred noise that I may use in the future. A 1k resistor is 4nV/rtHz and would swamp out the benefit of a true LNA.
Now, on to Dave's very long power-efficient PI idea...
Happy New Year to all,
Carl

[g.s]

Listen to to me carefully κτ315 is a very interesting EVERYTHING YOU posted by you ..
I have spotted another problem in DELTA ..
look in pin 9 for 556 ...


I try to change that with a attiny 45 Did you know about programming can help...
Here I am programmer avr

[kt315]

DP on AVR has been released many years ago.( not by me!)

[g.s]

KT315 what is the period of delay at tr2 amounts(us) is.. from the initial pulse ΤΧ (ΤΡ3)..