BK 3010 Function Generator

I recently took a trip down memory lane and purchased the first function generator I used in high-school the BK 3010. I acquired this unit off ebay for an exorbitant $35 CAD. Now this isn’t a truly original BK 3010, this unit has been hot-rodded by some lady in the Physics department. You will note the front panel location that once held a TTL output banana jack now has a fine frequency adjustment knob. Secondly on the rear of the unit, there is a sliding toggle switch to enable/disable the DC offset adjustment control.

Having glanced through the schematic included in the user’s manual for the B&K 3010 there a few interesting design choices.
The negative supply rails are derived off unity-gain inverting amplifiers with a discrete pnp output buffer. This would ensure the positive and negative supply rails are highly symmetrical in magnitude. I’m not sure what a 79xxL series regulator would have cost in the mid-seventies so, I’m not sure if there is a cost saving here too.

Eat my dust, say’s the 75107 to the 555.

You will note the designer opted to cross couple the 2 nand gates in the differential line receiver to form an SR-Latch with active low inputs. With propagations delays listed typically below 20 ns, this makes for a screaming fast, 555 style building block component. I don’t know who designed the BK 3010, but I think she did a great job!

Of course, how can you not admire the overdriven differential pair in the CA3086 transistor array yielding a hyperbolic response. Which is used to shape the triangle waveform into a sinusoid.

Enjoy some photos:

Comment always welcome. 

Haven’t decided what to replace the power connector with. Maybe the Mickey Mouse IEC C6, not sure…

Having dedicated knobs and buttons for every parameter is nice when your trouble shooting and debugging, using the instrument just seems to happen as second nature (no fumbling through menus). Though very rarely do I want a signal below earth ground, and am constantly adjusting the dc offset and amplitude back and forth to get a unipolar signal.

That is fascinating. The core VCO appears to be almost identical to the BK3010. Interestingly they splurged for the full power rated 78xx series regulators but then cheaped out on the negative 5 volt rail with a basic zener.

It appears your unit will read out the function generator’s frequency on the counter with out routing a patch cable to one of the inputs.

That is like my BK4017A:


I don’t think any of these modifications (except maybe a new power connector) are necessary for basic audio troubleshooting. 

You can also start a forum post asking for function generator recommendations 

Take care:)