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Topic: I think we might be a little expensive. (Read 190 times) previous topic - next topic

I think we might be a little expensive.

I'm attaching the cost analysis and the numbers are pointing to a suggested price of $62.
 
  The suggested price is based on the following:
  Sheet 2 shows the same type of cost analysis done for the Arduino. The   Arduino has a 70% markup when 1K quantities are used, I always try to   match that number since it should be safe to assume that is what our   market will support. Going below that means that when it comes time to   make a discount for resellers our margin goes below 50%, in my mind that   is bad because that means the resellers make much more money then we do   (remember we split our portion of the markup).
 
  Assembly costs are not included because I don't have any way to know what the Arduino assembly costs are.
 
  If we ignore the suggested price and go with $49.99, which matches the Flashy price, then we have a markup of 63% and if we give a 30% discount   to resellers then we have a 47% markup.
 
  So I think if we are ok with a $49.99 price then we should see if we can squeeze out any better pricing on parts somewhere.
 
  What do you guys think?
 

Re: I think we might be a little expensive.

Reply #1
Good cost-analysis! The only thing I see missing are the female header contacts which should be included but not assembled in my opinion.

If we aim at a suggested sales price of US$ 99 for a kit consisting of the OLS and the DSO wing (without probes/cables) then the suggested sales price for the DSO wing could be as high as US$ 56,85 (US$ 42,15 for the OLS).

For comparison: Flash/Flashy has no input stage with range selection.

- Flash single channel 70MHz (one ADC08060) is US$ 49,95 without the BNC metal-cast connector (adds US$ 4,95) and header connector (adds US$ 2,95).
- Flashy single channel 200MHz (one ADC8200) is US$ 59,95 without the BNC metal-cast connector (adds US$ 4,95) and header connector (adds US$ 2,95)

Re: I think we might be a little expensive.

Reply #2
Do you have any suggestions for reductions?

I didn't realize the opamp was that pricey, maybe there's a substitute. I'll do some looking.

The ADC is a big expense, but it's pretty similar to all the other ADCs I've seen.

The relays are the next biggest item. We could have a fixed DC input range (+/-12volts), or make it adjustable via [s:]a trimpot[/s:]. I would consider a cheaper v1 with manual adjustment, then we have an easy new feature to add to v2 (as well as low-end and high-end models).
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Re: I think we might be a little expensive.

Reply #3
Obviously a trim pot is a bad idea, but some form of manual selection (jumper, switch), or a fixed range.
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Re: I think we might be a little expensive.

Reply #4
I didn't get much time to think about it because I went straight to bed after finishing the spreadsheet. But I think we might be able to get inspiration from looking at the older Flashy models. I seem to recall that when I was researching DSO's, way back when, I came across some project that did it in a cost effective way that I thought would be good for our first revision. Maybe it can be as simple as a rotary switch that connects to different resistor values?

Jack.

Re: I think we might be a little expensive.

Reply #5
Basically any alternative to relays, a manual adjust method.
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Re: I think we might be a little expensive.

Reply #6
The Flash/Flashy boards never had an input stage with flexible/selectable range selection ... they advise the user to use resistors to adjust the dynamic input range:

Chapters 8 and 9 (in particular 9.2) of the KNJN Flashy acquisition boards documentation

Quote
9.2 Extended dynamic range
To go beyond Flashy's native limits, use an external resistor divider (or a potentiometer) to reduce the voltage seen by
Flashy. This is easy thanks to Flashy's native high impedance input stage (1MΩ).
For example, a 1KΩ/9KΩ resistor divider can be used to divide by 10. With a 10:1 probe, that allows signals between -50V
to +100V to be probed.

V-pos and V-range are controlled within stringent limits (max. -.5V to +1.0V with a 1:1 probe/direct input respectively -5V to +10V with a 1:10 probe) by potentiometers and DACs.

I don't think this is what we want to do - HF rotary switches are not cheap either ... don't we want the software (client) to know and to control the dynamic range?

Beyond that I don't see a considerable market for a "DSO add-on wing for the OLS" without range selection - it would be a fast ADC add-on with a preamp stage and would have rather limited use as a "tool" ...

For good reason Michael already kept the design at the bare minimum required to call it a DSO add-on - it has no trigger logic (so a trigger could be implemented in the VHDL design), no external trigger and clock input, no vertical adjust ...

Re: I think we might be a little expensive.

Reply #7
There is another approach.  Use a 12 bit ADC like the TI ADS805.   It has a sample rate of 20MSPS and has an input range of 5V. We would use a lower cost opamp configured the same way as we have now the input to the opamp can be +-2.5v.  That results in ~ 1mv per ADC bit.  We eliminate all of the relays and use a single voltage divider on the input.  Ranging would be done in the FPGA/PIC by throwing away lower order bits.  You lose the AC coupling and Gnd reference but my scope probe already has a gnd ref. besides x1,x10.  The ADS805 is more expensive Digikey.

McZ
"Too many projects, so little time"