HammerHead Build Blog

[geoscash1]

Well, finally decided to build this project, something I bought quite sometime ago but never got to it because I just didnt have the knowledge when I got it. I now understand the components better, how the pi operates and have a better understanding of using my scope so decided its time to build the venerable Carl Mooreland Hammerhead.

At this moment, the build is started and per the build doc have just finished steps 1 & 2 the power supply & oscillator section. Step 1 and step 2 both check out nicely with all voltages correct. Will add pics as I go so to log the process for everyone to follow along that may be interested.

Anyhow in the mean time, I would like to ask anyone that has built this project, what option did you choose, option 1 vco or option 2 non vco, which option is the better choice in your opinion. I have been leaning towards the VCO but every unit I've built to date so far has been vco other than the surf or cuda. After reading about option 2, non vco, it doesn't sound to bad either so am stopped in the build procedure until I make a choice.

Will post some pics in a bit.

Geo

[geoscash1]

Ok, just ran into the first issue, the option 1 & 2 documents do not match the rev D board or diagram so is there a Rev D option 1&2 doc anywhere, I am not finding it...

[geoscash1]

7660A and power supply

Power supply built. 7660A is the 12v version and that is what was used here.

Ic2/pin1 = +4.98v
Ic3/pin3 = -5.02v
Ic4/pin3 = -5.02v

Ic2/pin3 input = +10.7v (using 12.6v supply)

[geoscash1]

Clocking Section with 555 & components

Clock oscillator section installed, tested and good to move on.

Ic5/pin1 = -5.02v
Ic11/pin8 = -5.02v
Ic12/pin8 = -5.02v

Ic5/output TP1 = -0.8v (w/R3/R4 centered)




NOTE:
After installing this section and continuing to read on in the build doc, I noticed it says "Do not install Q8-Q9. Make sure all appropriate shorting wires are placed for this option." (somehow I did not see this the first 11 times I read this)

What and where do any shorting wires go, I looked over the doc and am not finding that info anywhere, help at this point would be appreciated.

[homefire]

The Jumpers are not shown in documents for Rev D. Use Rev C Placement.

[geoscash1]

The Jumpers are not shown in documents for Rev D. Use Rev C Placement.[ATTACH]37501[/ATTACH]

Thanks homefire.

I have looked the drawing you posted over numerous times but my RevD board doesn't have the holes for those jumpers in it, it doesn't even match up to that. In fact, it looks like a couple of the spots have the jumper trace already in place with no need for using a jumper.

[homefire]

Not followed all the changes. Just went by the project list and comments on only a few changes for the Rev D. They must have redid the board at some point.

[geoscash1]

BIG PROBLEM - R VALUES Labeled Twice ???

Well, started into the TX portion of the circuit this morning and low and behold, found an issue within the doc for the transmit section of parts values.

See image below, R17 & 19 is shown in option one parts list as 2 different values, which is correct for this application.



It would be great if Carl or George could chime in with their advice....

NOTE: Just found this - http://www.geotech1.com/forums/showt...st-%28opt-1%29

[geoscash1]

Not followed all the changes. Just went by the project list and comments on only a few changes for the Rev D. They must have redid the board at some point.

Yea, I agree, it looks like the board has changed quite a bit since the RevC. after looking at the board I have (from Silverdog) and comparing it to the docs it looks like it has the jumpers installed as traces in the board so looks like no jumpers are actually needed.

I would love to hear from silverdog or Carl to make sure this is a correct assumption, I would hate to screw up my only board...

[geoscash1]

Ok, I am stopped for awhile until I can sort out the TX section, very confusing with understanding what the active pull down, passive pull down, R7, R8, R9, R15, which parts to add which to leave off .... uhhgggg.....

I want the faster turn off of Q3 but am not quite understanding which parts to leave out or to add to get this correct.

I think I am understanding this as, Quote - "however, an active device pulling down the gate/base of Q3 will achieve faster turn off than a resistor" , so using Q2 as the active pulldown then I leave R7 off and jumper it or short it and then use R15/10k for Q2 base, still keeping R8 to divide down the voltage at the base of Q3 or is this incorrect.... good gracious, I am seriously confused now.....lol

I think I need a drink, oh wait, that probly wont fly with my chemo....never mind, maybe just a strong cup of coffee and a pain pill for the massive headache I'm about to get.....

[geoscash1]

More confusion, after calling out R8, nothing is mentioned in the doc as to what it is and none of the drawings show it ?
Also, what is R14, not in parts list or the drawings either, yet it is on my board?

[Tim]

R14 is second (RX?) damping resistor. R8 is 100R at emitter of Q2. Looking at HHd1 schematic on Geotech1. Maybe the 2 separated points on this schematic at gate of Q3 represent the active/passive pull-down options?
I haven't started this build yet, but have previously read all options and versions. As I have 9 boards I will make the first bog-standard to avoid confusion.
I can imagine there would be some confusion for RevC builders.

[geoscash1]

Burnt toast smells way better!

R14 is second (RX?) damping resistor. R8 is 100R at emitter of Q2. Looking at HHd1 schematic on Geotech1. Maybe the 2 separated points on this schematic at gate of Q3 represent the active/passive pull-down options?
I haven't started this build yet, but have previously read all options and versions. As I have 9 boards I will make the first bog-standard to avoid confusion.
I can imagine there would be some confusion for RevC builders.

Well, I let the smoke out..... the doc you posted is different than what I had so that is a big part of the problem too..

I got the correct voltages at all points thru the process but after adding what I thought was a jumper and some parts that weren't in my parts list but on my board, I powered up and burned the mosfet and the 555 along with a smoked resistor. It did have sound for about 20 seconds while I was trying to adjust the threshold, then it went up in flame... oh well, off to the shelf for a later trouble shooting project..

[homefire]

Sounds like the Mos FET found a path to Ground. Were did you put the jumper ?

[Tim]

I think I need a drink, oh wait, that probly wont fly with my chemo.........

I'm looking after Mum now while she recovers from having half her guts ripped out. Pretty sure the imported doctors got the Kilos and pounds mixed up with the Chemo dose- it just about killed her. To add insult to injury, she has a procedural hernia- the muscles didn't mend properly. But she's a tough old bird, and in good spirits now. I've had to give up work-hence the delving into electronics, and doing my Cert II Horticulture. Hopefully she will get the all-clear on the 5th. Then she can get the hernia fixed. Eventually I will get back to the shearing sheds (Woolclasser by trade). It's a great job to get to far-flung and remote places- with lots of old relics, and a few gold occurrences. And to socialise and co-habit with real salt-of-the-earth, tough, hard working, thick-skinned people. I don't drink any more, so weekends will be spent detecting, and evenings on the soldering iron.
Sorry to hear about your run-in with the tap-dancer Geocash - something I wouldn't wish on most. A mongrel of a thing. Keep your head up matey.