Archive for September, 2012

ECC81 tube radio

I’ve seen a lot of circuits with tubes at low voltage ( max 20V ), so I wanted to experiment with one too,… and what could be more fun to play with than a radio.

I started from a short-wave radio schematic with an ECL82, in which I replaced the ECL82 with a ECC81, which I knew could work at low voltage, and did a little tweaking with the resistors, and coils.

ecc81 radio schematic

L1 = 4 turns, L2 = ~40 turns, L3 = 4turns, in this order on a ferrite stick. ( the fun part is to play with these coils and the variable capacitor, until you hear something ).

Note, that all the values are not strict, tweak them as you see fit.

I’ve also had great results leaving aside L1, and connect the antenna by a 100pF capacitor directly in L2.

Have fun.

Custom select input

Using some jQuery and CSS you can make a cross-browser custom select (dropdown) box.

<div class="select-wrapper">
        <option selected="selected" value="1">Option 1</option>
        <option value="2">Option 2</option>
        <option value="3">Option 3</option>
        <option value="4">Option 4</option>
        <option value="5">Option 5</option>
.select-wrapper {
  position: relative;
  width: 215px;
  height: 30px;
  padding: 0 25px 0 0;
  margin: 0;
  border: 1px solid #0D5995;
  overflow: hidden;
  background: url(select-arrow.png) no-repeat right center transparent;

select {
  position: absolute;
  left: 0;
  top: 0;
  opacity : 0;
  width: 240px;
  height: 30px;
  padding: 5px 0;
  border: none;
  background: transparent !important;
  -webkit-appearance: none;

.select-wrapper span {
  display: block;
  width: 210px;
  height: 30px;
  line-height: 30px;
  padding: 0 0 0 5px;
$(document).ready(function() {
  $('select').after('<span>' + $('option:selected', this).text() + '</span>');
  $('select').click(function(event) {
    $(this).after('<span>' + $('option:selected', this).text() + '</span>');

See the demo.