SURF PI 555 QUESTION

[Constantin]

By th way, the 555 can also be configured as a negative voltage generator instead of the ICL7660 or the LT1054.

Is necessary a particular frequency to avoid interference?

[Qiaozhi]

i appreciate your advice George with the hammerhead design to get around the problem but ive had no luck even getting the coil drive to work on the hammerhead which i made over a year ago...similar problem excessive current being drawn and mosfet over heating...which is another one of my project problems maybe with the surf pi i will just have to be happy with 16v to the coil.

You've probably got mixed up with the various options on the HH. It can be a bit confusing which links to insert, and which to leave out.
For the transmitter, you only need to insert the link that connects the gate of Q3 to the junction of R8/R9.
The other link is only there if you want to experiment with active turn-off.

[daverave]

ok will check that out...be nice to get the HH working as spent many hours on this and got nowhere.

[daverave]

ok will check that out...be nice to get the HH working as spent many hours on this and got nowhere.

i have now got the coil drive working but yet another problem with the hammer head with high frequency tone on the audio and no threshold working...this has been a head ache for me since building it over a year ago...just too complicated...never had these problems with surf pi.

[kt315]

what you have on IC8b input pin 5? did you set the switch AUTOTRACK or not? do you set the switch in open state or not?

[daverave]

hi kt
pin 5 of IC8 has 0v when no coil connected....the threshold control has no control over this constant tone coming from the audio...im not sure if this tone is the threshold or some internal problem that is over riding the threshold tone ...i have tried both the auto tune on and off......this hammer head has been much frustration for me to get working.

[kt315]

do you make VCO rev or without VCO? did you set IC9 or not?

[daverave]

i tried the non vco option.

[kt315]

try this. a pitch is/no?

[daverave]

you want me to connect pins 4 & 5...and link out cap ???

[kt315]

???

DESOLDER THE CAP & CONNECT THE LINK. what is NOT CLEAR SO I DRAW????

[kt315]

yup

[daverave]

ive got the hammer head working but with only the vco audio...the non vco does not seem to work for some reason...also i loose depth if i disconnect the auto tune function...ive got the vco running at around 300 hz as i do not like the click click audio...its a shame that the hammerhead was designed for only 12v supply...not sure if could be modified for 16v supply ???

[daverave]

been experimenting with the vco audio which i know very little about...when i scope the output of the vco chip the mark to space ratio changes when metal put near coil instead of frequency change...is this normal or have i done something wrong ????

[daverave]

i really like the hammerhead now ive got it working and also the vco is interesting...ive had to change different values of resistor to get the vco working but i may have to increase supply voltage to around 16.5 - 17v and hope the 555 does not go pop !!!! the ICL 7660 im going to replace with a different type with higher voltage rating.