[Thursday] Suggested Radio-Related Interactive Exhibits

Mon Aug 26 13:38:08 MDT 2019

You know after reading this I especially like the idea of adding an antenna to see if an increase of the range at which it is picked up by the portable receiver... although we might want to demonstrate when a weaker battery than a 9 volt, such as a AA under the idea of "dont try this at home"...

On August 26, 2019 3:33:58 PM David Caldwell via Thursday <thursday at newsm.org> wrote:

I like this. Fits in with the Morse code demo; involves a minimal amount of (unexplainable) magic; totally harmless and cheap. Could easily be expanded to teach some basic electricity. Encourages experimenting: more batteries (series or parallel?)=more distance or louder static? Effect of coin size? Could it work with a switch/key? Could you add an antenna/radiator? Can you receive it with a crystal radio?

On Mon, Aug 26, 2019 at 6:37 AM Craig Moody <cmoody3453 at gmail.com<mailto:cmoody3453 at gmail.com>> wrote:
Here's another idea for a hands-on simple radio transmitter that may pique a visitor's curiosity.  I found this cool little demonstration online:

By tapping the terminals of a 9-volt battery with a coin, you can create radio waves that an AM radio can receive.

1) Take a fresh 9-volt battery and a coin.

2) Find an AM radio and tune it to an area of the dial where you hear static.

3) Now hold the battery near the antenna and quickly tap the two terminals of the battery with the coin (so that you connect them together for an instant). You will hear a crackle on the radio that is caused by the connection and disconnection of the coin. Your battery/coin combination is a radio transmitter! It's not transmitting anything useful, just static, and it will not transmit very far, just a few inches, because it's not optimized for distance.

4) If you use the static to tap out Morse code, you can actually communicate over several inches with this crude device!

Craig

On Mon, Aug 26, 2019 at 12:06 AM Randall Snow via Thursday <thursday at newsm.org<mailto:thursday at newsm.org>> wrote:
Guys,

These are great ideas and I think we're starting a discussion that will have a huge impact in the years to come.  Ken, your list and component aspects are very thorough and engrossing.  Dave, you've summarized years of discussions and have a keen eye on all the possibilities for the museum's evolution.  Also, the website for the Exploratorium is great, and they have a lot of resources there we can explore.

A lot of this has to do with the long-term plan for the museum, and of course will be years in the making.  With Steam-Up on the horizon, we don't have a great amount of time, but I think one or two of these could be rolled out in primitive form at least.  I'm thinking we make it something quick and effective.

 A couple of versions of early radios that people can actually tune into a modern broadcast would be great.  Something as incredibly simple as a crystal set would be amazing to show what little you really need to receive a signal.  I'm hesitant to add in any sort of amplifier just because it detracts from the simplicity and could have people confused about what's going on in the black box.  Getting sound with some coils of wire, a chunk of rock ( or razor blade, or 1 diode) and no batteries will undoubtedly astound most folks.  Then of course adding a few steps of evolution in, open and working for people to play with, would be great.  Along with this, if there is time, and if we have the manpower for Steam-Up, we can probably run the "build a foxhole radio" session a couple of times during the day.  I'm a little torn on the typical razor blade idea.  I think the only way we could do that safely would be to glue them down to the base board ahead of time so they couldn't be handled.  I can also get blue tempered spring steel sheet in just about any thickness that we could cut up.  I'm just guessing that we could get that to work in the same fashion as a razor blade.  The other idea, safer and quicker, is just to use a modern diode in it's place.  It could be explained or even demonstrated to them how it would be done with the blade and pencil, and how a diode serves the same modern day function.  At that point they are being shown a tie to something more modern too and the functional relationship.

The radio tuning could be done in the wireless building, among the radios that are there, or upstairs in Massie.  Foxhole radios could be done outside if the weather cooperates or possibly in Mayes.  Let's think about these a bit more and see if there is time to make them happen or not.

Thanks, and I'm excited to see where the whole discussion leads!

Randy

On Sun, Aug 25, 2019 at 4:35 PM David Caldwell via Thursday <thursday at newsm.org<mailto:thursday at newsm.org>> wrote:
Just a few thoughts in no particular order.

1. Some exhibits can be engaging without being interactive. Some people like to play with stuff; some people like to look, read and figure stuff out.
2. Many visitors, especially on busy days like Steam-Up, won't be with a docent and won't take the time to sit down. We need some exhibits that are 'self-service. (This is related to #1.)
3. It's important to decide at the beginning of planning who the audience is for a particular exhibit. Every exhibit has to assume some things about it's intended audience--what ideas they are familiar with, what language can work for them (eg, vocabulary, complexity), physical dexterity, etc.
4. We need to consider potential accessibility issues.
5. We need to consider safety always. Safety of the visitors, and safety of the artifacts and exhibits.
6. We need a mix. What works for kids isn't going to engage retirees who have been hams from childhood.
7. Exhibits need to be bulletproof--always working, durable-- especially self-service ones and browsable displays of artifacts (see #5)
8. We should consider taking advantage of the devices people carry around with them.
9. We need to start at the beginning, as Ernie suggested. Many people, and not just those under 30, have no idea what electricity is nor much of anything about how it works, no clear idea about what a radio is or does (they just expect sound to come out of any box--a radio, a TV, an iPod, Alexa), no understanding that the driver for almost all the history on the wireless side of the museum is communication (getting a message from one place to another) not entertainment, and no awareness of all the codes that make it possible (Morse code, ...)
10. We should look for examples to emulate and borrow from, and not only radio museums. The Exploratorium (https://www.exploratorium.edu/exhibits) comes to mind. And Spark (https://www.sparkmuseum.org). The best of them seem to take little bites--exhibits that each try to get an 'aha' about just one important concept in one small chunk of time.

Dave

On Fri, Aug 23, 2019 at 11:19 PM Ken Carr via Thursday <thursday at newsm.org<mailto:thursday at newsm.org>> wrote:
This post is mostly directed at the NESWM hams.
Suggestions and comments are welcome from all.

Randy has asked for some suggestions for additional interactive (engaging)
radio-related displays at the museum.
We already have an excellent start with the interactive displays in the
wireless building. I believe Craig and several other people were responsible
for that (my favorite is the little tubes that light up ... can't recall their name).

Below I have a list of some suggested exhibits. One of them, the scanning
disk TV, was suggested by Chris Prata last Wednesday night as we were
touring the museum with some guests.

The list I came up with is short on particulars and I'm not sure what is
workable. It is just a bunch of quick ideas.
It would be good if everyone could come up with a list and we could all
discuss particulars.
----------------------------------------------------------------------------------------

Interactive Radio Displays

Operating an old radio

Computer station displays photos of a sampling of old radios from NEWS collection... Clicking on any radio brings up 3-minute video of that radio being operated. Show a little about what was done to revive radio, feature period ads from catalogs or museums for this radio, and finally show how to operate it. Period accessories should be used (headphones, speaker, meter to monitor filament voltage, radio premiums of period, etc.)

Can you play this radio?

Complex looking radio receiver is on small desk with table. Sign no. 1 with instructions (i.e. 1-5) guide patron to tuning in local broadcast station or our own transmission on BC band. Sign no. 2 is “Expert Challenge” which steps through process of tuning in live ham radio QSO in single side band (SSB). Demonstration includes antique headphones and antiseptic wipes.

Build a Crystal Radio in 5 Minutes or Less

Group challenge. Museum guide seats 5 patrons at radio construction booths (cubicles) arranged in semicircle. Booths and walls feature photos of crystal radios and accessories from our collection along with period advertising. Docent gives 5-8 minute talk about crystal radios and specifically fox hole radio. Each cubicle has instructions (displayed on placard) for constructing radio. Docent passes out parts kit to patrons and tells them to begin making a radio. Docent provides guidance if needed. Each person’s first name is put on scoreboard with time they took to make functional radio. As patrons leave they are given handout that illustrates how to make 3 different crystal radios at home: simple, intermediate, advanced. Learn More: Web and book references provided at end of handout.

Morse Code Challenge

1 Watch short video or read simple instructions on placard on how to operate code key.

2 Patron follows instructions and sends message with straight key. Message is ‘received’ on computer screen (old iPad running audio to code interpretation app). Patron encouraged to persist at keying until message is ‘properly received’ (display reflects what patron intended to send).

3 Advanced Challenge no. 1: Perform as above with sidewinder key.

4 Advanced Challenge no. 2: Perform as above using antique wireless age key and sounder.

Antennas : Make an antenna. Docent demonstrates how radio without antenna receives nothing. Then constructs dipole. Next switch in dipole that is outside and tune same spot on radio.

Or: Station consists of radio and labeled antenna switch (A, No antenna; B. 10 foot wire; C, Outside dipole). Patron switches antennas to demonstrate difference.

Match The Tubes: Patron presented with 5 different vacuum tubes from different eras (tubes are in a basket or wood block with hollowed out areas to receive tubes). Below are five descriptions of each tube in chronological order.  Patron must place proper  tube in the slot with the matching description.  This encourages  them to read about the different tubes and recognize features.

Bonus: If they get the tubes in the correct order they will light up and radio station will be heard. To make this work each tube has a stiff pin/wire or dowel attached to its central indexing tab. Pins vary in length. If all pins are placed correctly each one will activate a relay in a string of relays which collectively will turn on the radio.

Make the Radio Work;  Circuit diagram of radio is drawn on wooden easel. The drawing has actual binding posts and tube sockets. Hidden below is a real radio. At each position where a tube belongs there is a real tube socket. Flip chart explains how to ‘activate’ the radio:

1 attach the indoor antenna (patron ties in antenna with alligator clip and lead … 10 foot wire antenna)

2 Insert mixer / converter tube, no. ****** (text briefly explains what this does)

3 Insert First IF tube, no. ******* (text briefly explains what this does)

4 Insert 2nd IF / detector tube no. ******* (text briefly explains what this does)

5 Insert audio amplifier tube no. no. ******* (text briefly explains what this does)

6 Turn on radio (volume/on switch attached to board)

7 Adjust station with tuner control

8 Unhook antenna lead and attach to bigger antenna (antenna no. 2, up 25 feet outside)

Tune a Radio:

1.      Presented with a 1920’s regenerative radio. Instructions show how to turn on and tune. Patron does so. Warned about excessive feedback and howling. Turn off and go to second radio.

2.      Presented with a 1920’s 3-dialer (Tuned Radio Frequency) radio. Proceed as above

3.      Presented with a 1940’s superheterodyne console radio. Instructions show how to turn on, tune station, and turn off.

At each stage patron is informed about merits and faults of each design.

Do You Cohere?

Station has several coherers that work on different principles.

Patron is briefly informed of function of coherer and is then encouraged to make each one work.

1.      Patron dials up power on rheostat and then presses code key (massive) and sends ‘spark wireless radio transmission’ (actually a nearby but hidden transmitter is activated).

Audio creates sound of spark transmission. As rheostat voltage is increased more of the coherers activate , thus demonstrating the relative sensitivity of each design.

Coherers begin to cohere and as they do a sounder next to each is activated just once.

2.      Next the theory of the decoherer is explained and patron performs same task as above but with set of coherers that include decoherers. Constant buzz with interruptions (long and short Morse code characters) is heard. Communication is now possible.

Amplify This !

Patron is presented with working crystal radio. It is explained that since they work on very little current (whatever is present in the radio wave itself) it is not enough to make loud noise. How might they make it louder (amplify)?

Solution no. 1  Attach two sets of earphones to one crystal radio so more than one person can listen in. Unfortunately with the addition of each earphone the volume in each is reduced.

Solution no. 2 Make the output of the earphone reverberate against the walls of an expanding horn. Connect earphone to the end of a horn speaker. (Randy's idea)

Solution no. 3 Attach output of crystal radio to a crude amplifier. We may build one or better still attach the crystal receiver to the kind of amplifier that was sold as an accessory to the Radiola III (we have at least one of these on display in the museum. I suspect more are squirreled away somewhere). Other solutions are offered in various crystal radio enthusiast books. We can also provide tube and transistor-based amplifiers that can be switched in from a control panel.

Create Electronic Components From Scratch

Patron presented with samples of production electronic / radio components. Each is explained and its operation in a circuit is demonstrated (connect to circuit, push button to activate, effect seen on attached meter, lamp, speaker, etc.)

Next patron is given material to ‘make’ their own components. They then test them by inserting into circuits. Resistors and capacitors may be taken home. Printed labels provided for outside of capacitors and resistors.

Everything is run on battery power, no high voltage danger.

Components: Resistor, Capacitor, transformer

Mechanical Television Camera

Mechanical television camera is activated by patron and image of patron is seen on vintage TV (round porthole style) CRT. (Chris Prata)

Library

Open the library for study by anyone. Although we will not lend publications, patrons are free to purchase photocopies of select pages of old publications. We make the copies and charge 50 cents per page (or whatever fee schedule that gives us some revenue and keeps the patrons happy). The library can have rotating theme displays that feature such items as: original patents, advertising illustrations, collections that address one particular field, etc.

Posters that are reproductions of illustrations might be on sale in the library.

Radio Drama Room (Old Time Radio)

Small groups (5-20 at a time) enter our ‘living room’ which is set up like a living room from 1939. There is a large console radio with a tuning eye, a rug on the floor, upholstered couches and chairs, etc. Make it look just like 1939 … real comfy. When everyone is seated the radio comes on (a child patron is asked to do the honors). The lights dim and the only bright light in the room comes from the radio. An announcer comes on and does the intro for today’s show.

It may be The Shadow, Buns and Allen, Johnny Dollar, Jack Benny, etc. Choose titles that are appropriate to the season (horror during the fall, Christmas shows in December, etc.). The show will run for about 20-30 minutes. The room should be well ventilated (AC) and sound proof.

Make a radio transmitter in 5 seconds

Display radio is tuned to portion of the band that does not have a station playing. The patron is given several items with which they may create electric discharges through the rubbing together of dissimilar materials. If the humidity is correct (low humidity, dry weather; AC will help) they will hear the discharge on the radio. Placard explains that this was the basis for early spark transmitters. Note that the emission can be heard anywhere on the band. This would never work for broadcast radio. Eventually radio transmitters that used vacuum tubes and finely ‘tuned’ circuits were able to create distinct ‘radio stations’ on specific frequencies.

How is your Radio Eyesight?

Present patron with an operating radio that has a tuning eye (magic eye, miniature cathode ray tube). Explain the theory of how it works. Encourage patron to ‘tune’ the radio to various stations using the tuning eye for accuracy.  If possible lighting should be subdued at this exhibit. Point out how the eye opening varies with signal strength.

How do you put a value on an antique radio?

Display 6—10  antique radios and speakers. They are in various states of repair and completeness. Provide overall guide as to what features determine the value of a particular radio. This can be text that is displayed above the radios or it may be audio that can be accessed with earphones (disinfected earphones like those in airplanes are given to all patrons with admission ticket).

After listening to the audio discussion on radio values the patron uses a  ‘score card’ that is keyed to the display radios. They must grade each radio on certain characteristics and finally put a dollar value on the radio (pencils available). When they have completed the score card they press an ‘answer’ button that reveals the values and explains why each radio has a particular value to collectors.

Radios of Rhode Island

Special exhibit put together by Len A.

How is a radio restored?

Static exhibit of about 5 models of the same radio, each showing the progression of steps involved in restoring that radio.

Interactive Analogue Demonstration of Stages of Superheterodyne Radio Receiver

Most explanations of how a simple superheterodyne radio works are too complex or vague to keep a person’s interest or to convey understanding. If each electronic stage of the superheterodyne radio is displayed alongside a working mechanical (not electronic) analogue of the separate stages it may be possible to illustrate how a radio works in an intelligible manner.

The setup:

Front and center (controllable and accessible to the patron) are 6 working devices that convey each successive stage of a radio receiver. None of these devices are electronic or necessarily electric. They demonstrate physical properties or observed mechanical phenomena that are similar (analogous) to the electrical or electromagnetic functions of each stage of a radio receiver. Some examples (not necessarily accurate):

Tuning forks and multiple piano strings: fan dipole antenna as a medium that electronic vibrations (radio waves)  pass through and vibrate within, some better than others, due to ratio of antenna length to waveform length. (Represent antenna by fan dipole).

Structure consisting of mass suspended by springs and set in motion by eccentric drive which reaches maximum amplitude when spring-capacitor and mass-inductor are in phase or what would be called resonance in radio circuit. (p. 444, Sutton, Electrical Oscillations). This mimics the local oscillator of the radio.

Competing waveforms may when they collide result in addition and new (sum) waveform is produced as demonstrated in rod model (p. 139, S-28, Sutton (1937). This is analogous to the mixer stage of radio although in a radio sum and subtraction of RF is produced. The difference is the frequency that is selected out. This mimics the mixer section of the radio. (Note: the mixer and local oscillator are usually combined in one vacuum tube and together referred to as the converter stage.

The output of the converter / mixer is fed to the Intermediate Frequency stage which is a circuit tuned to a particular frequency. It has an amplifier (tube) that is optimized to amplify only that one frequency, the intermediate frequency, which is allowed to pass through this stage and pass to the vacuum tube for amplification. Analogue representation of this stage: 4 different tuning forks are tapped. In front of them is one piano wire. It only responds (vibrates/ oscillates) in response to one of the four tuning forks since its length allows it to vibrate optimally at just one frequency.

And so on through the remaining stages of the radio.

Behind the Mechanical models is a large labeled and color coded block diagram of a radio.

Rather than a block diagram you might use actual radio parts within the blocks.

Activating any physical model will cause the analogous radio stage to light up. Where appropriate actual radio tubes (with clear designations in front of each) can be used. Safe DC battery power would be applied to filaments only as each stage is selected.

Finally patron will be encouraged to turn on the ‘radio’ and tune in a station. 5-part fan dipole has numerous colors (frequencies along its length). Only one color at a time appears in ‘glow’ of the converter stage. Local oscillator (LO) within converter stage has a different color. The color that emerges from this stage and goes to IF amplifier is always the same color as the LO (others are filtered out). As tuning dial is rotated you see that the color entering the converter stage change, one color for each station frequency.

And more stages follow …….

This display could have several things that the patron could control. A lot of planning would need to go into this. It would be good for an electrical engineer to supervise the design.

Comments and additional ideas welcome.

________________________________

Ken Carr ...
KE1RI, A New England Ham<http://www.idlenot.com>
Westerly-Pawcatuck AACA<http://www.wpraaca.com>
N.E. Steam & Wireless Museum<https://www.newsm.org>

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