Hammerhead Rev D discussions

[Carl-NC]

There is a 10v version and a 12v version of the 7660. Try running the 10v version anyway, it might work fine. If it burns up, replace it.

You could also try placing a couple of diodes in series with the 7660 supply pin. It really doesn't need all 12 volts.

- Carl

[Ray-NM]

7660 voltages

Having a little problem with the 7660 ic. Anyway I was reading the specs on the 7660 and it says 10v max on the input. the schematic shows 12 v so how do we get away with the extra 2 volts for the input power?
RayNM

[Bill]

Charles it looks like we both ran into the same problem, those damn 0.47uf caps from mouser are too big! I always use calipers to make sure what I am ordering will fit but these slipped through. I ended up buying some wima types at a local supplier. Looks like you also went with metal films, our boards are almost identical!

Bill

[Ray-NM]

Thanks

Ordered my parts today so should have them by the weekend and get mine put together.
Thanks for getting the boards to me so quickly Carl, The do look good.
RayNM

[Charles (Upstate NY)]

Ain't it cool! I dub it...Darth Hammerhead. Reaches out a hand and in his best Darth Vader voice says...Don't be too proud of those other technological detectors, they are insignificant to the power of the PI Force!

Alas, I ordered the wrong 100k pots and my 47 caps were way too large for the board so construction is haulted until I can order the parts next week.

[Carl-NC]

The way the 555 timer works in astable mode, it normally generates a pulse with a >50% duty cycle, which happens to be what we want for the "normal" design. However, I included an option to use "active pulldown" for Q3, by connecting its gate to R7. In doing this, you would need to invert the 555 pulse, which can be done by adding the diode and changing R1-R4.

- Carl

[Charles (Upstate NY)]

Carl I'm curious about D8, I see you left it off the mono build. Seems new to this board. I looked at the schematic, can't really tell why one would include it or leave it open. Thanks!

[Carl-NC]

IC7 is the 4066 chip; a b c d are the 4 gates inside that chip; d is not used in the design. This is a common issue with schematics, where a physical chip can have multiple circuit items. IC8 is another example, where one package contains 2 opamps. My schematic software doesn't let me delete gates that aren't used.

The jumpers on the right are for audio options. The one on the left is for the mono coil... leave it off, add the 2nd damping resistor, and you can use a DD coil.

- Carl

[Charles (Upstate NY)]

Carl I took a pass at compiling a complete parts list below based on the schematic.

Couple of questions,

1. IC7d is floating all by itself in the schematic, can you provide any guidance on this?

2. If I were to build the board for a DD coil would I simply populate the board with all the appropriate parts? I noticed you jumped a few parts and left a few parts off in the mono loop board you put together.

3. Can you comment on the areas marked in red in this picture. Appears that you jumpered them? Would this be the same for the DD?

Thanks!

Charles



R22 (see text)
R11 (see text)
R14 (see text)
1ohm R10
27ohm R20,R21
100ohm R8
220ohm R9
330ohm R46a
470ohm R54
1k R12,R24,R25,R28,R36,R39,R55
1.5k R4,R42a
3.3k R7,R40
10k R5,R6,R15,R37,R43,R44,R45a,R47,R48,R49,R50,R51
22k R52
30k R53
56k R1
100K R17,R19,R26,R27,R29,R32,R33,R34a,R38
150k R30
1M R13,R16

Pots
100ohm R23
5k R41 (or 10k Audio Taper)
5k R35
10k R3,R42,R46
50k R45
100k R2,R18,R31,R34

C16 (see text)
1n C11
10n C8,C24,C25,C26
0.1u C17,C18,C22,C23
0.47u C19,C20,C21
22u C3
47u C4,C5,C6,C7,C14,C15,C27
100u C1
1000u C10

4066 IC7d (not sure about this one)
74HC221 IC12a,IC12b,IC11a,IC11b
7660 IC1
78L05 IC2
79L05 IC3,IC4
555 IC5,IC9
NE5534 IC6
4066 IC7a,IC7b,IC7c
TL072 IC8a,IC8b

2N3904 Q2,Q8,Q9,Q10,Q11,Q12
2N3906 Q1,Q5,Q6,Q7,Q13
IRF740 Q3

1N4148 D1,D2,D3,D4,D6,D7,D8
LED D5

SW1 1
SW2 1
Speaker 1
Terminal Block 3 pin
Terminal Block 6 pin

[Carl-NC]

For HH parts, I've found Jameco to be an excellent source, with about the lowest prices. Here is a list of major components:

[FONT=Courier New]Sch.#   Part#     Jameco#   Price
IC1     ICL7660   290301    1.35
IC2     78L05     51182     0.27
IC3,4   79L05     51422     0.25
IC5,9   LM555     126797    0.51
IC6     NE5534    27406     0.78
IC7     CD4066    13186     0.35
IC8     TL072     33195     0.26
Q3      IRF740    210569    1.25
Q3alt   IRF640    210542    0.69
Q3alt   IRF620    210526    0.45
Qxx     2N3904    38359     0.69@10
Qxx     2N3906    178618    0.46@10
Dxx     1N4148    36038     0.36@10
Rxx     Trimpots  3296Y-xx  1.69
C14,15  47u/10v   546100    1.03
C14,15  22u/16v   545852    0.40[/FONT]

Most other components are ordinary R's and C's. Remaining polarized caps are electrolytic, non-polarized caps are monolithic or poly-types. R's are 1/4W, you can buy a nice 500-assortment at Radio Shack for ~$12. For non-trimpots, Jameco has panel-mount pots at $1.15, and for on/off/volume they have a 10K audio taper pot/switch combo (Jameco 263636) for $1.59. 10K instead of 5K for R41 is fine.

Also, the PCB has space for 200-mil terminal blocks for supply, speaker, and coil(s). You would need (3) 2x blocks (Jameco 152346, $0.65) and (1) 3x block (Jameco 152354, $0.47).

[Carl-NC]

Although these boards turned out very nice, I did notice that a few plated-through holes have metal stringers that must be cleaned out in order to insert the component lead. Maybe a half-dozen holes per board. I just stuck an X-acto blade in the hole a twirled it.

[Carl-NC]

Here are the PDFs for the main schematic and parts placement. These are for all possible configurations, so keep in mind that some parts are not used, or get shorted, depending on the configuration. Specific options will get posted next.

- Carl

[Carl-NC]

This thread is for discussion of the Rev D board.

At this time...
I have NOT tried out the various audio options, just the VCO (opt 1).
I have NOT tried a DD coil, just a mono.
I have NOT created any documentation except for the schematic and parts placement diagram.
I probably will not revise the HH article for this board, at least not any time soon.

Therefore, some things will get worked out as we go, based largely on feedback from early builders.

- Carl