Articles

Electronics fair in Göteborg

9/3/2017

The 8th and 9th of March it was time for the big electronics fair in our home town. Röcklinger was there to take part of the event. Many interesting things to see and new contacts were established. As you may know, we have new products and new designs under development and we are looking for reliable partners to work with. It seems like Hans enjoyed the fair and was very happy with the outcome, you decide.

Input impedance analysis

15/2/2017

This is how we at Röcklinger set up LTspice for input impedance analysis

Use a current source with the fixed magnitude of 1 Ampere:

In parallel with the input.
In a point in the circuit where analysis is required.

A shut resistor is not needed if Rinput is in parallel with with the current source. In other cases use a 100G resistor in parallel with the current source.
From Ohms law we find that U = I * Z and as the current source is set to 1 Ampere then in this case the magnitude of the Voltage is equal to the Impedance.
Do an AC analysis and plot voltage of interest divided by the current source. Set the scale of Y-axis to linear and voila impedance is ploted.

Burst of DC supply

31/1/2017

Here is another tip for you to tackle a possible problem with burst of the DC supply. As usual we at Röcklinger are happy to share our knowledge for those interested in detail construction.

In order to take care of the burst in the input we recommend the following circuit design:

The circuit above keeps + and - together at the feed to the logic. If you still have problems with interference it is usually due to that the voltage across the component supply inputs are different due to different ground capacitance at different locations on the PCB. Usually, the fault lies in the ground plane in these cases.

Surge protection in DC input

3/12/2016

We at Röcklinger are very happy to share construction and design tips for you out there who are exploring the wonderful world of sound perfection and creating your own circuits.

In order to protect against surge in DC inputs, bidirectional diodes such as the SM15T39CA from Microelectronics for instance, are very often used. The location of these diodes define the characteristics that the input circuit will have. If you place the diode fore the common-mode choke coil the diode and fuse will break when you put a disturbance in the DC input. Instead, place the diode after common-mode choke and you get a resistor in series with the diode thus limiting the inrush current.

Output transformerless links

9/11/2016

The first amplifier Röcklinger launched was a headphone amplifer, build with tubes and with OTL technique. OTL stands for Output Transformer Less. To learn more what OTL is we share with you some usefull links for the curious.

OTL Amplifier - Background and OTL Circuits - go to link
6C33C OTL - go to link
Tubecad article 001 JRB - go to link
Tubecad article 002 JRB - go to link

To measure input impedance

22/10/2016

We at Röcklinger always simulate the electrical design first, then we build the circuit, measure and improve the design. This loop continues until we are confident that the final design is flawless. We also like to share and prove our design. So here is a tip on how to simulate input impedance using LTspice.

Use a current source with the fixed magnitude of 1 Ampere:

In parallel with the input.
In a point in the circuit where analysis is required.