400Hz HH

[Unregistered]

I want to retune my Hammerhead on 400Hz frequency.My coil is 300mkH - 2om. Any sugestion for main puls with, sample with and second delay i want to be fiksed.

[bbsailor]

Go to the following web site for a good 555 calculator. http://www.daycounter.com/Calculator...lculator.phtml

First, plug in the values that the Hammerhead currently uses so you can understand the inverted output concept. Once you obtain the right values, that pretty much match the Hammerhead design, you can then increase the value of the capacitor and resistors in the calculator to obtain a new set of values in a lower PPS range that varies between about 200 to 600 Hz.

Note that the target response would be slower and that you may need to experiment with a different integrator capacitor (C17 and C1 value of about .2uF. If you plan on using a large coil with long pulse widths, you will also need to heat sink the MOSFET and use a one or two watt damping resistor. You may need to adjust some other timimg parameters to get the best responses from this new frequency range such as a longer pulse width range up to about 150 to 200 us.

The most practical way to approach this is to draw out the published Hammerhead pulse train timing for the lower range of 900 PPS on graph paper showing the microsecond distance between TX pulses with all the other pulses fit between, including: TX pulse width, main delay, RX sample window, secondary delay, secondary sample window. This will allow you to scale the various pulse parameters at about 450 PPS to be proportional to the Hammerhead design. Just make sure that when you choose a new pulse range that all the necessary pulses fit within your new full range of frequencies.

bbsailor

[Esteban]

Hi Bbsailor

I use this calculator in Bill Bowden's page. Always this calculator requires the RA resistence. For example, I need a frequency near 8.7 kHz, 50% duty cycle. The second calculator always requires the lowest resistence and show interval times positive and negative in milliseconds. See the small difference:

[Qiaozhi]

You can also easily do the calculation yourself with the following formula ->

f = 1/T = 1.46/([RA + 2RB]C)

where RA is the resistor between pin 7 and VCC, and RB is connected between pins 6 and 7. The capacitor C goes from pin 6 to ground.

The duty cycle D = RB/(RA + 2RB)

[Esteban]

OK, is very easy to calculate with this formula. Thanks.

[Unregistered]

400HZ

Thanks for answer!Main puls 150mksec., sample puls- 35mksec., delay- 25... 45mksec..
Please,any sugestion for sekond delay to be fiksed.