Archive for category prototype

Frequency compensated attenuator tests amplifiers

We’re working on a low-noise amplifier product, and to test it we need some attenuation, to generate clean low-level signals. The pdf shows a schematic and describes some test results. It’s a little more tricky than just a couple resistors because with every resistor you get (free!) parasitic capacitance that tends to distort your signals, unless you compensate the network.

Based upon Motchenbacher and Connelly’s excellent book ‘Low Noise Electronic System Design‘. Click on the link for the pdf or on the image for a JPEG version.

pdf: Build-your-own-wideband-attenuator

Build your own wide bandwidth frequency compensated attenuator to test amplifiers.

No Comments

Prototype, progress, and the first digital camera

We make prototypes. Sometimes it’s hard to imagine how a product will evolve from the first (clumsy?) prototype into a sleek product, once it gets ‘real’ and becomes a manufactured (perfected?) item.

Since we all know what digital cameras look like now, here’s a photo (ironically a digital photo) of an early Kodak prototype digital camera, to show how things change and improve: (note that we don’t need the cassette tape to store images any more).

The full article can be found here: link to story about first digital camera at Retrothing

No Comments

Light uniformity testing

For both a clinical test microscope, and a home theater HDTV projection display, the light from the source must be quite uniform.

To test some non-imaging illumination optics, we set up our digital camera, and wrestled with the RAW data files from the camera. Most cameras have some ability to ‘see’ infra-red, so we can also test the pattern from the remote control output, or for other purposes.

Here we test the light uniformity of an LED source using a digital camera and some Thor Labs mounts.

Here we test the light uniformity of an LED source using a digital camera and some Thor Labs mounts.

These graphs were generated by ImageJ from the RAW data files of the Nikon D1x camera.

These graphs were generated by ImageJ from the RAW data files of the Nikon D1x camera.

, , , ,

No Comments

Custom front panels

Here’s a vendor we recommend, and a photo of some parts they made for us.

photo of parts made by Front Panel Express for our Diff Amp project

When you make one or 10 of something it can be difficult to make it look ‘real’, that is, to make it look finished. Sometimes the Dymo-Marker labels are OK, say in a sci-fi movie, for your Custom Flux-Capacitor. But other times, you want the prototype to look clean.

We have enjoyed using the services of FrontPanelExpress to make some custom front panels for our projects. They provide free software, that’s simple and easy to use, and you upload the files to their on line ordering … and you get great parts back. A variety of anodized aluminum options and thicknesses.

They will engrave text, add paint colors into the text -makes a very nice professional looking prototype or short run of parts.

Just imagine – they can easily make a D-shaped hole for the BNC – so it won’t UNSCREW and FALL OUT !!! That alone is worth the price of admission. I can’t find my D-shaped drill bit …

They can do a lot of things that are a pain to do by hand – countersink holes, nice RS-232 type D-cutouts, square holes, etc. Check out their site for some examples.

We also made a Plexiglass panel – this allows us to compensate for the very annoying differences in height of the switches and knobs – and it allows simple paper graphics to be protected. We also considered making a glowing logo, but have not yet done that.

, , ,

No Comments

attenuators, connectors, etc.

Here’s where to get quality attenuators and connectors

Testing any high gain low noise amplifier requires a nice clean attenuator.

You need to drop the level of your function generator,

or that x1000 gain amp would need to supply 100 V output.

Pasternack Enterprisese sells a nice 30dB atten for about $42.

Their part number is PE7000-30.

If you put 2 of these in series, you have about x1000 attenuation.

(These assume a 50 Ohm load, so buy one of those too).

Here’s a link to their website:

Pasternak weblink

, , ,

No Comments