*Function Generator 1MHz*

Requirements:

a. Waveforms sine, square, triangle
b. Variable frequency
c. Variable duty cycle
d. Variable amplitude
e. Sweep function
f. Astable or monostable operation
g. Mains powered
h. Metal enclosure
i. Analouge schema using pots, switches and buttons
j. Can be built for under $50

How would you do this one?

 

Except for the sweep function it sounds like one I built around an Exar 2206 function Generator chip. It cost more than $50 bucks in 1976 and I bet it would cost more now.

https://www.sparkfun.com/datasheets/Kits/XR2206_104_020808.pdf

 

The right solution is to use a microcontroller. STM32 with built in DAC is perfect. The whole boad is $10.

If you insist on an analog solution, search for 30 years old designs around MAX038.

 

Except for the sweep function it sounds like one I built around an Exar 2206 function Generator chip. It cost more than $50 bucks in 1976 and I bet it would cost more now.

https://www.sparkfun.com/datasheets/Kits/XR2206_104_020808.pdf

I have used the XR2206 IC in an previous design. Sold some units on eBay.
Looking for something different now.

 

The right solution is to use a microcontroller. STM32 with built in DAC is perfect. The whole boad is $10.

If you insist on an analog solution, search for 30 years old designs around MAX038.

Actually I am thinking of something that uses many discretes.
Like a dozen or so OP AMPs.

People will learn more from this, and it will take some time to build. Lots of people like soldering boards with lots of parts.

 

Actually I am thinking of something that uses many discretes.
Like a dozen or so OP AMPs.

People will learn more from this, and it will take some time to build. Lots of people like soldering boards with lots of parts.

Lots of questions...

What frequency range? You need some fairly fancy op-amps for over a few MHz of operation.

Does variable amplitude include an output attenuator? An output amplifier with 50 ohm output impedance is needed for high frequencies.

Log or linear sweep of both? Log sweep is trickier than linear sweep but it is most likely what you want.

How important is the monostable operation? By this I assume you mean trigger and gate modes?

How important it the $50 dollar limit? Pots and knobs are expensive! The metal box alone can be more than $50.


Maybe you should look at old Wavetek models and tell us which one you like. The model 181 is a good one to look at first.

 

I would compromise on whatever to meet the $50 target.
There is psychology floating around that suggests that most people think long and much harder about spending more than $30.

I have purchased metal project enclosure from Taiwan for $7.50 landed (on eBay)
Pots, knobs, buttons & switches are cheap enough through Tayda Electronics (Taiwan)

I feel something can be done for $50. A toy perhaps. But still something.

 

Why not use a 8038 (ICL8038, XR8038, MAX038) or XR2206?

 

Why not use a 8038 (ICL8038, XR8038, MAX038) or XR2206?

This is what I would do. But keep in mind that all of these old parts may be, or will soon be, obsolete.

The project will still be interesting when you add all of the other stuff needed to do what you want such as an output amp, trigger/gate circuit, attenuator, power supplies, log sweep circuit, enclosure/front panel, etc.

p.s. I would go with the MAX038 The MAX038 is no longer made but parts are still available.

 

Here is an example of a 10 MHz function generator. It is a design I did a long time ago. Features include: variable symmetry, AM, FM, trigger/gate, a 50 ohm pulse output and a 50 ohm waveform output with adjustable DC offset.

This is the function generator I use the most although I have others including one done using a MAX038.

This is only for reference since many of the parts were expensive when I did the original design and are hard, if not impossible, to get now.

 

Maybe I should realize the 21st century and go with an digital system.

 

Maybe I should realize the 21st century and go with an digital system.

Just like a digital scope is not the same as an analog scope, a digital signal generator is not the same as a function generator.

Disclosure: I like my test equipment to have knobs and switches and not keyboards.

 

Just like a digital scope is not the same as an analog scope, a digital signal generator is not the same as a function generator.

Disclosure: I like my test equipment to have knobs and switches and not keyboards.

But either way it is an no winner right? Electronics has now become an situation whereas everyone just wants to do their own thing.

 

But either way it is an no winner right? Electronics has now become an situation whereas everyone just wants to do their own thing.

Sorry, I don't follow what you are getting at.

 

I would compromise on whatever to meet the $50 target.
There is psychology floating around that suggests that most people think long and much harder about spending more than $30.
...

If you are going to be making something to sell to "people" for $50 I don't think there will be any significant profit in it.

Kits sales are at all time lows in the last few years.

 

How about building something around this? Kinda dumb on the subject. Just trying to help.
http://www.amazon.com/Huhushop-TM-G...merchant-items&ie=UTF8&qid=1407206842&sr=1-33

 

If you are going to be making something to sell to "people" for $50 I don't think there will be any significant profit in it.

Kits sales are at all time lows in the last few years.

That's what I mean by 'no winner'

Whole thing has gone belly up. No money anywhere.